I am just getting around to installing the light switches . This is how the finished light switches look at the moment. Later on I plan to change the front plate of this switch to one of the other options such as glass, wood or marble.
This is what the above light switch looked like before installation. Standard switches can be used if one uses the method described below. I used a screened alarm cable to connect the KNX binary device known as a universal interface. This voltage is extra low around 3 volts DC.
As seen above this is what a typical KNX lighting distribution board looks like. One has a Power Supply (top left) and a programming Interface (next to power supply) . The three actuators (12 way) on separate rows send power directly to the rooms or other devices such as towel heaters. Functionality such as timers, last state before power failure, purging (automatically switching on pumps/valves to ensure they do not stall) etc is already built into the KNX technology.
This is one type of LED Driver I have used to power each LED. Typically when one buys an LED they have already tried to fit all the electronics contained in the above unit in the lamp one buys . This is one reason why led lamps do not always live up to their expected life time of 50,000 hours. The majority of LED failures are due to heat stress. I am using 9 watt LED in the housings shown above and the Power supply is a separate unit. For lower power LEDs one requires less electronics.
Floor laying continues with the Junckers System. The floor boards are 22 mm solid wood with a proprietary clip system. Each of the metal clips (shown below) connect each floor board. The clip type one selects depends on the expected humidity levels in the home. I used a soundproof underlay on the concrete floor. One can also nail this type of flooring.
Skirting Board Lighting
I started the design of the skirting board lighting that will be powered from a DC source (battery) connected to a solar panel. The idea is that this lighting would be on when it is dark and would also act as a lighting system if there was a power failure in order to minimise the use of candles.
The light output of this lighting would be equivalent to a candle and they are placed in bathrooms and corridors in order to allow one to walk around the house at night without switching on the main lights.
A first fix of how they will look is as shown below.
Different HRV units have different mounting options. Some are floor only, wall only or ceiling or all three. Some units like the Airflow DV145 that I purchased can be mounted on the floor or wall while smaller Airflow units can be mounted on the ceiling, floor or wall. One needs to make sure that there is space underneath for the condensing water outlet. If the unit is mounted on a wall make sure that vibrations do not interfere with noise sensitive rooms such as bedrooms. I mounted ours on a sound proof and isolated base and used other sound proof methods to isolate it from an adjacent room.
In the early stages of the build the fresh air inlet and stale air duct positions were selected with a spacing of over 2 metres. If the supply and exhaust ducts are too close this can interfere with the correct operation of the HRV unit. This entailed finding an HRV unit that would be flexible in the options available to simplify the space required for the main ducts and keep the runs as short as possible. The lengths of the supply and exhaust ducts play a big factor in the efficiency of the whole system. The Airflow unit comes in a right hand and left hand model. I found that different manufacturers have different duct layouts even though they have Right Hand and Left Hand models.
DATA from the HRV with the Post Heater On
One can see from the above graph that with the winter sun I needed to switch of the heater and switch to summer bypass. The next plan is to automate the bypass mode when the solar irradiance level measured in W/m2 and temperature exceed a set value then the HRV would automatically switch over to the summer bypass mode as one is gaining solar heat.
As the internal fans are to the rear of the unit I added a small amount of soundproofing as an experiment. I was able to reduce the db level from 49 db to 44 db. Each 3 db approximately equates to twice as loud or twice as quite depending on whether you are increasing or decreasing the level.
I mounted the unit in the hallway entrance so extra sound proofing was required. If one has a utility room then extra sound proofing would not be necessary I feel.
Following on from the previous blog I had a display panel built that calculates the HRV efficiency using the supply method and extract method by means of the Modbus data connection available in the HRV unit . In the Image below one can see S100 (Supply method for calculating efficiency) and the E 90 (Extract method ) as a percentage. The supply method is the one typically used by manufacturers in brochures. The D displays the difference .
The top line displays the temperatures of the Inside air and the air leaving the house followed by the Outside air temperature and the supply air temperature to the house. When the post heater is on the efficiency calculated with the supply method sometimes displays a number greater than 100% as the heater is built into the unit and mounted before the thermostat. The extract method for calculating the efficiency is a closer representation of the real efficiency and it is similar to the passive house method (uses the same principle ). The extract method does not use the supply air temperature in the formulae.
Access for repair and maintenance.
Some HRV units require side panel access so ensure that you have enough space to get access to fans/ filters for cleaning and maintenance . The Airflow DV145 can be fully maintained from the front cover so it can be fitted in a corner space without restricting future access to internal parts. The filters are also maintained from the front panel.
Functions and Benefits
When selecting a unit- what was important to me that there was an integrated summer bypass function in the unit, software control by a smartphone with data capture (a manual control panel-is an extra cost and another item that could fail) and an integrated post electric heater. Airflow also sell a ground source heat pump option connection to the HRV which I did not purchase. For those installing a stove / fireplace one requires a Fireplace function built into the HRV . The Airflow DV145 has this function.
September 2018 performance.
The summer bypass function allows one to bypass the heat recovery function during warm weather or reduce winter sun peaks (when the sun is low on the horizon). The way this works is to bring the air outside directly through the ducts in order to reduce the internal temperature at night or during the day. One can see from the image above on the 28 and 29th of September I forced the HRV unit to summer bypass during the day to keep the temperate under control with the winter sun. No heating had been switched on for the month of September and the night temperature outside has hit the lowest in the same month of 2 degrees.
The Airflow unit is software controlled by means of your phone or your personal computer . This helps keep the HRV cost down, gives remote control and it provides data for analysis. The physical manual control panels in general cost €200 or more.
The post heater in the Airflow DV145 unit has a PWM (pulse width modulation) heating element control which means that it can control the switching of the heater within a fine tolerance for heating the air rather than just switching the heater On and Off. The reason I installed this was really to provide a back up option to the main house heating system (approximately €200 extra).
House Heating System
The house heating is currently designed around two storage heaters of 1.7 kw each to heat the house using off peak electricity and operate for 7 hours a day. I picked up one unit for free and the other unit cost €70. I suppose one could say that the total capital cost of the heating system was €270 when one adds the HRV post heater.
For the month of October one of these heaters was switched on for 14 days. The post heater also improves the frost protection functionality within the HRV and helps maintain a heating level of 21 degrees Celsius throughout the house.
Below is an example of how the HRV switches on different heating loads in the post heater while maintaining a set temperature . The time interval below is over 60 seconds (full screen view) and the heater appears to adjust the power output required continuously to maintain the set temperature.
Duct work for primary supply and extract
I selected an insulated 210mm EPS duct for the extract pipe as this duct carries the coldest air from the HRV unit .
Supply and Connecting Manifold Ducts
There are a number of options. My understanding is that the larger duct systems such as 150mm feeding multiple rooms with silencers is the best option if one can accommodate this in the build early on and find a good designer. I opted for the 91mm semi rigid ducts using a manifold system from https://www.fraenkische.com and I am very happy with the low noise level and amount of air being delivered throughout the house. I use a co2 sensor to monitor how the flow rates are working in different rooms.
When one is designing a house to the passive house standard or installing an HRV unit in an energy efficient /airtight house one can reduce the cost on the system if one plans the service routes of the ducts early on and selects particular joist types. It is expensive to batten and counter batten to hide the ducts afterwards as one needs to try and keep the duct-work within the airtight envelope.
I opted for the manifold system using the largest semi rigid ducts I could find. These were the Fraenkische-profi-air classic pipe with an internal diameter of 78mm and outside diameter of 91mm. The larger the duct the lower the air friction and noise when delivering air to rooms such as bedrooms. These ducts are also anti-static and low emission.
Below are the choices I came across from the semi rigid range. The white duct is made by Fraenkische.
Connection ducts from Manifold to HRV.
For the ducts that connect between the main HRV unit and the manifold I used an insulated flexible sound reducing duct (as seen below). This is made up of an inner foil with sound reducing properties, next an airtight plastic membrane and then insulation followed by another layer of foil. The inner rim is re-enforced with a steel wire to provide rigidity. It is time consuming connecting this up but it appears to have done its job.
There are principally three methods it seems. One is the Supply method (used by manufactures) and this usually gives a higher efficiency value than the real world values. The Extract efficiency method is used to give a closer to real world value and then the passive house efficiency method which adds the following formulae to the Extract efficiency method.
Pel = real electrical power, W
M = mass flow, kg/h
Cp = specific heat of the air, kJ/kgK
The good news is that it appears if the HRV is certified to the Passive House standard then the difference between the supply method and the extract method is very small.
In the near future I plan to connect to the HRV unit I purchased and view the efficiency values.
The Passive House certificate shows the following
The most cost efficient unit I came across was the Airflow DV145 passive house certified unit for our 200 m2 house with an airflow capacity of 542 m3/h. I paid around €2200 for it. If one has a smaller floor area then more savings can be made by using a smaller unit. As a self builder technical support was important and their main offices are in the UK.
If one opts for a non-certified HRV unit a 12% reduction must be applied to the manufacturers specification . Some manufacturers might not renew the certificate each year so it is a good idea to ask if a certificate exists. The data must be entered in the planning software for the passive house. For those interested in the passive house planning software (PHPP) there are courses run in Ireland frequently so I would suggest that one does this 3 day course (typical) and usually one finds the software discounted on the course.
It is an enjoyable course where one can select your own pace (the first time I did the course I wanted to listen and learn rather than calculate the performance of our own home). One such place is http://www.passivehouseacademy.com/
There are two types of HRV units that I came across -Heat (HRV) or Energy (ERV). The ERV is used principally for recovering humidity and heat. I selected a HRV unit,
When selecting a HRV unit it appears that one of the biggest mistakes is to select a unit that is too small but still satisfies the current regulations. What appears to happen in the competitive world of quotations is that a unit that just ticks the box comes in as the best price.
In selecting a unit for our home I selected a unit that has a manufacturers capacity of 542m3/h where the floor area of our house is 205 m2. Currently the unit is running at 31% of its capacity and it is maintaining a CO2 (Carbon Dioxide) level of around 700 ppm when the four of us occupy it . I use a stand alone CO2 sensor to measure the CO2 in different rooms. (I have not commissioned the unit yet as the internal doors/glazing are not installed).
Another advantage of selecting a larger unit is that it can run more efficiently at lower speeds and generates less noise through the ducts or from the unit itself.
Some of the options from the manufacturer Airflow (my unit is the third from the right).
September 2018 performance (with no heating switched on yet).
The graph below gives an idea of how the HRV works when managing heat from the house and supplying fresh air. For the coldest days of the year so far (2 degrees at night-in September) I put the unit into summer bypass mode the next morning (take in outside air directly and pump it around the house) because the sun was shining that day. The winter sun is lower in the sky so solar gain increases in the winter (when the sun shines). The house is made of timber/glulam construction. The main thermal mass is the concrete floor at the moment soon to be covered by a 32 mm thick wooden floor so the response times of house I suspect will change. The floor and wall temperatures are approximately 22 degrees Celsius.
Example above of HRV in use in our home.
Sample Data in our home using Google Fusion to visualise the HRV data for a week in October. (see link below)
One can select the chart tab and visualise the graph.
Use the bottom graph to zoom in.
The data is from the 21 October to the 28 October 2018.
One storage heater rated at 1.7kwh was used for 5.5 hours a day off peak.
The storage heater was switched off for one day on the 23rd October.
The graph starts at midnight on the 21 October.
Each ref reading is every 10 minutes.
The CO2 reading vary between 480ppm and 700ppm when fully occupied.
All HRV units contain a maintainable part called filters. They have a number of functions.
Clean the air being pumped into the house, and
Keep the internal components such as fans, ducts and HRV housing clean.
One typically finds one coarse filter and one fine filter on the air supply into the house and a coarse filter on the extract air from the house before the extract fan. The coarse filter is typically a G4 and the fine filter is a F7 (Pollen filter). I installed a 400mm x 400mm G4 coarse filter at the duct inlet so that I could keep the main supply duct clean. It is a bit more effort to maintain this but it will hopefully minimise the maintenance of the duct.
Self Build air tightness test -0.22ach with a volume of 603 m3 @ 50 pascals.
When one is building to a performance standard the day of reckoning is the airtight test. The reason for this is that when one is pumping fresh air into the house using a Heat Recovery System, rather than relying on simple multiple holes in the wall, it becomes important to control where the fresh air is coming from and where the heat is going.
If air is leaking in or out around windows /doors/walls or other gaps in the building fabric then heat is lost and moisture problems in the form of mould can arise or else give rise to damage to the building fabric.
The pressure 50 pascals equates to a 20 mile per hour wind which is not too untypical in Ireland. So if one opts for the Irish building standard (a minimum standard) this equates to the air in the house changing/leaking 7 times a hour when a wind blows at 20 miles per hour. No wonder people block up the hole in the wall vents .
The current Irish building standard require 7 air changes per hour (ach) also called leakage at 50 pascals typically with no heat recovery system. As a guidance heat recovery manufactures recommend 3 Air leakages per hour to ensure that the heat recovery system can push fresh air into the house and recover heat leaving the house through its own system rather than through gaps in the building fabric.
The passive house standard for a new house requires 0.6 Air changes per hour (ach) at 50 pascals to ensure the heat recovery system works efficiently, ensure that occupants receive the correct amount of fresh air and minimise building fabric damage.
The passive house test differs from the Irish test because it must include pressurisation and depressurisation and use the volume as set out per Vn50 (EN13829).
Gavin O Shea from Greenbuild was hired for the job. He is certified/audited by the National Standards Authority of Ireland (NSAI).
The preparation for this entailed sealing all cable ducts and the inlet and outlet pipes for the Heat Recovery System. One also ensures that the shower and sink outlet traps are full of water. The overflow outlet for two water tanks were not sealed off. I did consider a duck valve but it was not in place at the time of the test.
The test using the Irish method gave a result of 0.181 m3
Gavin O Shea calculated that the equivalent size hole that equates to a result of 0.22 ach is approximately 65.25 cm2 (@50Pa) or a hole 81mm x 81mm if all of the leaks present in the dwelling were concentrated into one hole. That is about a tenth of an A4 sheet of paper.
The results of the air tight test can also help determine the selection of the Heat Recovery System. If the airtight test is lower then more options are available when selecting a unit.
From my research a passive house standard Heat Recovery Unit will cost more because it needs to be independently tested by the Passive House Institute using their test method. Heat Recovery manufactures have also the burden of putting the unit through national tests or international tests with the end result being the customer pays more. One has also the option to select a non passive house certified unit for a passive house but when calculating the performance value one needs to account for this in the PHPP software with a 12% reduction below the manufacturers performance claim.
If one wants to view certified Heat Recovery Units one can find and sort them at the following link. One can see for example at this link the capacity (Column- Air Flow Range) that these units have as it is important to select a unit that is oversized for your particular self build. I would compare it to selecting a mini car to tow a caravan up a hill compared to using a larger car. The small car will struggle from an efficiency and noise point of view while the larger car will be quieter and more efficient at the require flow rates. I will do a separate post on how I selected our Heat Recovery Unit.
I finally switched on the water supply to the house and then checked the compression connections on the gravity based system for leaks. The reason for using the gravity based system was to keep everything as simple as possible, consume the lowest amount of energy and have a system that would be low in maintenance cost. All the joint connections were brass compression fittings and I used a pipe called “qual-pex” . I insulated the cold and hot water pipes for both the rainwater and the calorifier tank.
I installed a separate gravity tank for the toilets that will be fed from the rainwater tank in the garden eventually. I need to design a control unit to pump rainwater when required and operate from the mains to flush out the gravity tank at regular intervals. At the moment it is connected to the fresh water supply for testing. This tank was mounted 2.71 metres above floor level. Nylon washers were placed inside and outside of the tank brass connections fittings.
What worked for me in relation to the toilets was an 1/2 inch pipe that ran a distance of 15 metres approximately with a storage tank base to floor height of 2.71 meters and this enabled the cistern to fill in approximately 1 minute 45 seconds.
When tightening compression fittings- a good bit of advice is always leave room for an extra turn on the thread. In this way if there is a leak one can tighten the compression joint further.
On the calorifier connections use Jet Blue Plus paste or similar paste and check it is suitable for potable water.
The longest run was approximately 20 meters of 1/2 qual-pex and this supplies enough pressure for a “natural” water flow at the furthest away sink outlet-I also removed the filter in the outlet of the tap to further increase the water flow.
Certain isolation On-Off valves have bore diameters that are smaller than the diameter of the pipe bore further reducing the capacity of the water flow. Visually check before purchase.
Check that the taps and shower fittings are designed for a gravity system. I used a tap that had a minimum operating pressure of 0.1 bar from the Grohe range (1 metre height of water is = 0.1 bar).
I was unaware of what an air lock can look like . In one case no water flowed and in another case I had a constant trickle of water with no air gurgling. To get rid of the air lock I used a small 5 litre pressure sprayer with a silicone hose on the end.
Use copper inserts instead of nylon on “qual-pex” when trying to get gravity to work in your favour . They have a wider bore (see below).
As most of the inlet valves on toilet cisterns are now designed for high pressure they come with a restriction devices and sometimes a filter. For use on the gravity system I removed these.
I plan to filter the water at the feed end of the water supply. Both the toilet storage tank and the calorifier storage tank (supply’s the hot water) are within the thermal envelope. This means that the tanks will not freeze but this brings other issues to be dealt with, such as noise from filling and potential condensation. I installed rockwool insulation around the tank to minimise temperature differences of the indoor air and reduce the noise of water filling the tank as I have no attic space.
The original toilet had a bottom inlet valve made with plastic threads which proved difficult to install.
I did have problems with the original cistern valve where I cross threaded the plastic connection (which resulted in a leak) as one finds that space is limited under a toilet/cistern (see below).
Another problem I had was I could not get it to operate correctly from the gravity tank. To solve the above I replaced the inlet valve with a Jollyfill telescopic Wirquin brass inlet valve and removed the high pressure device.
When I installed the inlet valve the connection leaked between the rubber seal and cistern. I removed it and placed silicone above the rubber seal. The silicone cured the problem.
The gravity flow rate proved too low for the shower valve temperature control to work so plan B was acted on. I installed a 1.5 Bar 250w pump to raise the flow rate.
It is a Salamander RP50PT pump (45.5 dBA) . It cost €200 including postage. I am impressed with the low non-intrusive noise it generates. It comes with small sound isolating pads. One can roughly equate a 3dBA increase with twice the loudness.
Another factor to take into account when selecting and sizing a pump for one, two or three shower units is that the power usage approximately doubles when one selects a 0.5 bar increase for this range of pumps. So If one is sizing for the use of 3 showers being on at the same time (using one 3 bar pump) and only one shower is on then one will be using 1000 watts of power most of the time . I feel it is more energy efficient to install separate pumps and in this way one uses the least amount of energy most of the time and the pump will also be quieter as noise increases also with each 0.5 bar of pressure.
Having carried out some DIY painting in the past I decided this time I would invest in good tools as this was going to be the biggest job to date. This first entailed selecting a brand whose painting equipment is rated highly. I selected tools from the Wooster product range.
There are a few essential tools.
The Pole (I selected a 4 to 8 foot adjustable pole called the Wooster Sherlock GT extension pole ). This tool has a few good features such as snap on paint roller head, an extension that snaps in set positions, a tool to fit screw type paint rollers. A substantial rubber hand grip that made the job easier . The highest point of our ceilings are 3.6 metres and this version allowed me to reach the ceilings directly from the floor. Narrow hallways that are less than the length of the pole plus the roller would make it difficult to use this pole length.
Rollers– I selected a 3/8 inch nap (pile depth) for the plasterboard because of its smooth surface and I tried a 9 and 14 inch roller called the pro-doo-z. The Nap determines the amount of paint applied and the paint texture of the wall surface . The 3/8 inch gives a fine finish. If one used a 1/2 inch nap the roller can hold more paint but the texture is different. After trying the 9 inch and 14 inch roller my preference was to use the 14 inch roller as I found it easier, faster and more stable because it is supported at both ends (see below). I would be tempted to try the contract rollers that are supposed to be faster the next time but the finish may not be the same. One can select the right roller from the web site link Wooster Rollers.
Cutting In– A very useful and time saving tool was the Wooster hand-held Pelican kettle .
It is available with liners to make it easy to change colours. It has a section to hold a cutting in brush and a mechanism to hold a small roller. Both of these are necessary in order to end up with the same wall surface texture as the main roller for example around switches and sockets. I used non diluted paint for the cutting in process. One needs a mini roller also for the Pelican holder.
Brush– The cutting in brush I used was the Silver tip wooster 2 inch model. I never owned a high quality brush before and it is working out great.
Tray/Kettle-I tried the Tray and the Kettle. My preference is the 25 litre Kettle with replaceable liners. I initially bought a Kettle with no liners and the washing out of the tray or kettle at the end of a days painting is time consuming and non environmental as one must wash the inside completely . Comparing this to using a liner that one can dispose of in the bin. I know at the end of the day it all is non environmental but using plastic liners keeps everything clean and saves time.
Safety Glasses and peaked cap -While painting the ceiling it is a vital item.
Fresh Air– While the paint is wet the smell is stronger so ensure that your rooms are very well vented. As I am painting in the winter the house temperature has dropped to approximately 9 degrees.
Paint-I used Dulux paint as it has a good reputation for quality.
Cling Film-In order to keep the brushes and rollers clean I wrapped them in clingfilm overnight. The roller lasted a week and I did not notice any problems even with this amount of time . One just took of the clingfilm and started again with no cleaning required. It also reduces waste.
Technique I used for painting
First Coat– For the first coat on the plasterboard I mixed the paint to a 3 to 1 ratio (one litre of water to 3 litres of paint) as advised. By diluting the paint for the first coat it is supposed to allow the paint to get a good bond with the paper finish on the plasterboard. I did not use the traditional wet plaster method on the walls. The paint also needs to be mixed in a separate container. One requires a 1 litre container to carry out the measuring. I experimented with a lower ratio of water and I could not see much of a difference with the Dulux matt white paint on the bare plasterboard only that with two paint coats undiluted the finish looked better . If the walls were wet plastered in the traditional way then the water mix appears to be vital.
I started out using the paint brush and mini roller for the first cutting in but later on I just used the paint brush for the first cut and then used the paint brush and mini roller for the second cut in order to finish with the same texture as the 14 inch roller.
After watching numerous methods and comparing the comments I think the following is the best I have come across to date and having used the ideas it it all makes sense. With Youtube I found one has to watch about ten videos and then decide who is doing it right. Below may help.
When the first coat of paint is applied it often identifies small imperfections in the plastering. When this happens let the paint dry and fill the imperfection with USG or Gyproc ready made joint filler. When this has fully dried sand it by hand and repaint it with a few coats. This method worked for me.
The golden rule is-avoid sanding as much as possible by ensuring that the knife finish is smooth at the edges and as close to a final finish as possible. If one had to do this manually with a sanding block and pole it would be a tough job.
Thankfully over the years people have been improving the tools. I was lucky enough that the builder loaned me his sanding machine. I just needed a hoover to manage the dust which was picked up free on the free cycle web site. The sanding machine looks like the following:
Even though the above Flex machine makes the job easier and faster it still is a physical job especially when working overhead. The hoover was not designed for the above but it worked out OK once the bag and filters were cleaned regularly.
I would suggest safety glasses when working overhead and a face mask at all times.
Technique for Sanding Used
The joints had a second coat of plaster and then a touch up coat was used to remove any edges and at the same time look for and fix any imperfections on the butt finishes (where two boards are joined with no taper edge) or tapered edges. USG 3 Sheetrock (see previous blog) was usedfor the second and third touch up coat. I would not recommend the Gyproc joint filler for the second and third coat as it is primarily used for the first coat and it does a great job. When dry the finish is very hard and it would be difficult to sand. There is a Gyproc pro finisher but I found the Sheetrock product very economical and easy to work with for the second and third coat compared to other options.
I used a 150 grit sand paper on the Flex machine and left it at speed 4. I was expecting that the sand paper would get blocked up but this did not happen. I was advised and found it very important to sand the edges of the joints and ensure that one does not stay too long on the edges as the paper on the plaster board could be damaged. A light sand in the centre of the joint is how I finished each joint.
I also found it necessary to manually inspect the wall after the electric sander as one is too far away from the wall with the sander to spot imperfections. I made up a hand sanding block for this with a wood fibre board angled to get into corners.
The angled wood fibre board worked out better for me than dedicated sanding blocks and I used a pre-used sanding disc from the electric sander.
I experimented with the wall corner finishes on whether a sharp edge or rounded corners worked out better. The sharp edges looked like that shown in the top image below and the rounded corner is the image below that. If I was doing it all again I would use the rounded corners as I feel it looks better.
Typically with internal wooden stud walls there may be gaps between rooms at floor level or vertically. For this reason one may want to ensure that fire compartmentalisation is addressed (a previous blog covered this in detail). In order to do this I have chosen a B1 rated fire foam for the floor gaps. It also has a secondary benefit of reducing sound travel between rooms at these gaps. The foam I used was Olive PU-476. The price varies and the best value I found in Ireland was at National Seal Systems in Dublin. I also bought intumescent water based fire sealer for small gaps around the edges of the distribution board and vertical uprights where one partition meets another.
Plastering – Taping and Jointing. Tools and Lessons Learnt.
I finally completed installation of the plasterboard with the help of the mechanical plasterboard lifter and I have now just started taping and jointing. I decided on the international method of finishing the plasterboard rather than the Irish method ( see previous blog https://selfbuild.blog/2016/07/10/plaster-board-plan/) . If one is determined to use the traditional Irish method of wet plastering the whole wall I would still tape the joints with paper tape rather than the nylon/plastic mesh. The paper tape ensures the fire proof rating and from my research it is a stronger joint.
Below is an image of what it looks like when one applies the first joint filler tape coat. There are two to three more coats of plaster filler/compound required to hide the joints completely and some sanding.
I tried different methods and tools such as using a hawk instead of a mudpan to hold the plaster. For me the 12 inch mud pan worked out the best .
The tape dispenser is more important than I thought. The unit I purchased was a good design on paper but not very practical. If I was purchasing a unit again I would go for the steel design . The current model I am using is as shown below.
For ones own safety one must be able to roll the paper up after taping the joint as the hanging paper can become a trip hazard when moving around. I would try this steel one instead if I was starting again (see below).
Another item is a glove for the knife hand. If one is working with the filler for a few days I have found it to be very rough on the hands. Over time the skin will toughen up I suppose.
There are two main types for corner beads used for edge finishing . The steel micro edging (first image below) or the paper tape reinforced with steel (second image). I found it easier to use the steel micro edging rather than the reinforced tape edging. I tried a few methods of attaching the mesh and I settled for first applying the compound and using a few stainless steel staples(the standard ones are not stainless steel) to fix it securely while applying a finishing coat to fully bed it in. Note-ensure that one fully cleans the stapler after doing this.
The steel micro edging I feel is a better method to finish an edge and it is easier to sand and clean when applying wet filler.
Another idea that I did not get to try but it looks interesting is the use of pre-formed corner / edges using plasterboard. This avoids the use of beads and it is called the ZaapSystem from Prodar.
The reinforced tape comes into its own when one needs to tape two walls that meet with slight angles. The price of this varies from €15 to €30 for the same length.
I tried different fillers/joint compounds . Gyproc dry wall filler (it comes in a bag and is quick setting ). One mixes it with water and it requires the use an electric mixer to prepare it. This bag works out fairly economical but the time spent mixing, the dust, washing out the bucket every hour or so is very time consuming. Another disadvantage is that it sets very fast and is very hard to sand afterwards. The colour is also a disadvantage as it does not blend well with the plasterboard. An advantage is that it works out well when fixing the steel micro mesh.
The next product I tried is the Gyproc bucket version (pre-mixed) 15 litre. This is easy to work with but again it is a white finish which will make it harder to blend into the wall and will require more painting. It is also very expensive.
The best product I found and the most economical for the joint is supplied by Greenspan called USG plus 3 (it is an American product) and it comes in a 17 litre tub. It has the best colour blend for the board, it gives a finer finish, and is easy to sand. It does require a small amount of water to be added to make it extra easy to work with (this makes it go a bit further).
When applying filler near floor level increase the width of the filler to ensure that any skirting board lies flush against the plasterboard.
Use paper rather than plastic mesh for a stronger and fire safe joint.
Practise filing joints in a non critical area such as behind future wardrobes, en-suite or storage room etc.
Have a rag /clothe clipped to your belt to wipe away any dried plaster pieces before they get caught in the fresh new compound and leave streaks.
Use the 4 inch knife to remove any dried plaster compound or for checking screw heights. The other knives need to be protected from any edge damage or you will get streaking.
If the corner is less than 90 degrees I found it difficult to get a clean edge as there was limited space. In this case I made a finishing tool cut to the angle of the wall and ceiling with a rigid plastic cover to give a smooth surface.
I found it helpful to have the 4 inch knife stuck to the pan with a magnet. It saves some time bending down or climbing down the ladder to get it when using two other knifes. I typically would have the 6 inch knife for finishing edges and either the 10 inch or 12 inch for finishing butt or tapered joints. The 10 inch stayed in the back pocket .
Fully clean the knifes and dry them at the end of the day.
You will notice the difference between good quality knives and low cost knives.
If a knife should get damaged by a screw head I used a sharpening stone to repair it.
In order to minimise sanding sometimes it is better to re-apply another filler coat to get a perfect finish.
For corners I found it easier to use a corner knife (90 degree angle) and feather the edges with the 10 inch knife.
Use the 4 inch knife to clean away any small hardened plaster bumps before starting the second coat.