Category Archives: Tools and Aids

Plaster Board Finish

Wall Finishing and Fire Compartmentalisation

Sanding

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:

Sanding Machine
Flex WS 702VEA

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 used for 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.

Sanding Joint Filler
Edge Sanding of Plasterboard

 

 

 

 

 

 

 

 

 

 

 

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.

Home Made Sanding Block

 

 

 

 

 

 

 

 

 

 

 

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.

Self Build
Wood Fibre Board as a sanding block.

 

 

 

 

 

 

 

 

 

 

 

Plasterboard Corners

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.

Plasterboard corner finish straight edge. Note dust still on one wall.

 

 

Rounded Corner

Fire Compartmentalisation

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.

Self Build

 

 

 

 

 

 

 

 

 

 

Plaster Board Update

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.

Joint Taping
taping joints

I tried different methods and tools such as using a hawk instead of a mud pan 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.

Beads

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.

 

 

 

 

 

 

 

Fillers

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).

 

 

 

 

Tips

  • 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.
Plastering
Corner Plaster finishing
  • 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 .
4 inch Knife stuck to pan
Magnet on pan

 

 

 

 

 

 

 

 

 

 

 

 

  • 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.

plastering repair

 

 

 

 

 

  • 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.

Thermal Bridges

As part of the passive house requirement one needs to eliminate or minimise heat loss through linear lengths or points around the house. Some of the thermal bridges in my build are typical of other builds. I hope to provide more details in the future.

One of the main linear heat losses is with window/door installations (its connection with the wall frame ). It has been said numerous times that selecting a high quality window/door and installing it poorly can equate to buying a low energy window .

As mentioned before I will use the free software called Therm to calculate the losses. The first detail to tackle is the glazing which was directly mounted in the frame of the house without a window frame.  These windows are 2.4 metres x .9 metre and there are 11 of these mounted on the south face.

The calculation of these linear losses can be expensive to get done so I will be doing the task myself and have it checked by others. I am surprised that good details are hard to come by on the web for free to help the self builder. One of the most time consuming exercises with thermal bridge calculations is drawing the detail. If one undertakes drawing this oneself using CAD (Computer Aided Design) software it can help to reduce the cost of the calculation.

When one needs to come up with a detail to minimise the losses there are a lot of products that help to keep the losses under control. These are semi-rigid insulation products like compacfoam, foamglass blocks, standard insulation, TECTEM, PU or rockwool and fibreglass products and aerogels (which is one of the highest performing insulators being made).

To date there appears to be very few online resources to guide the self builder or provide details that one can use before one starts a build.

Some background and details I found to date on thermal bridges can be found at the following links.

What is a Thermal Bridge

Leeds Beckett University

Scottish Thermal Bridge Details Link

Example of Heat Loss through a glass spacer

Below is an example of the thermal bridge calculations one needs to carry out to establish the thermal bridge performance values in W/(mk).

  • One draws the detail as a DXF file using a drawing package (or draw the detail manually in Therm)
  • Import the detail into Therm Software
  • Add the technical details such as thermal conductivity of each item
  • Tell Therm where on the drawing to stop the calculation (Adiabatic)-top and bottom of the drawing shown below.
  • Tell Therm what the internal and external temperatures are
  • Go to a spreadsheet and calculate the psi values of the thermal bridge detail for the passive house performance value.

When this is done one ends up with the calculation and an image like that shown below. In this image the glass is shown near the top right.

Drawing Detail

 

In the next image the colours show the temperature gradients. The purple colour is the outside temperature at -10 degrees.

colour infrared
There is thermal bridge software that one can buy where the software calculates the psi value without using a spreadsheet but Therm is free and there are courses available in Ireland.

If one wants to show the real design and installation details of the thermal bridge values for the Irish regulations rather than the accredited details (without a performance value)  one needs to use a certified thermal bridge accessors but this is not the case for the Passive House Institute.

We can all look forward to the day when standard construction details that are typically used in Ireland are already calculated for the self builder and there will be no need to pay to find out the thermal bridge losses . The Scottish accredited details (see above link) come close to taking the guess work out of construction.

 

Moisture Control, Supply of Fresh Air, Removal of VOCs.

The Past

Having lived in an house that had single glazing and was draughty, I only realised how inefficient the ventilation was when I purchased a Carbon Dioxide meter (CO2) for the old house. This meter measures the amount of carbon dioxide in a room (as we all exhale CO2). The bottom line is that a level below 1000ppm (part per million) is taken as a healthy starting point. Another factor that is not healthy is Volatile Organic Compounds (VOCs) these are the chemicals, gases given off by furniture, paints, floor coverings, household cleaning agents etc. When one reads the possible health effects from VOCs it becomes clear that one needs to reduce these. See for example http://www.epa.gov/iaq/voc.html

In our last home what was amazing was how little oxygen we were getting especially when asleep (and in turn high VOCs). Within an half an hour the meter would alarm that the levels of oxygen (fresh air) were low.

What I used to do in the old house is determine if there was a wind blowing or a storm due. This then entailed adjusting the window opening to a minimum in order to ensure that we would get some level of oxygen. If there was no wind blowing outside then I would open the window  to approximately 75 mm (The horizontal window was over a meter and a half long) and leave the bedroom door open for some cross ventilation through the house.

I think it is now widely accepted that holes in the wall or opening windows does not work for fresh air and a healthy environment. The only way that appears to work is to blow fresh air in / suck stale air out.

CO2 Meters

CO2 meters for some reason are expensive. The unit I purchased was over €300 a few years ago. I came across a more affordable unit recently on ebay for approximately €100 (allow for customs and excise) that also has a data logger (records the information over time). I feel it is well worth investing in one of these as the true quality of air in a house can only be believed when the CO2 levels are measured.

One seller on ebay was perfectprimetechnology . If one types in the word co2 at their store it should be easy to find or in any other store. 

CO2 Meter
Carbon Dioxide CO2 Meter

While there is no direct link between VOCs and CO2 I have read that if one is breathing air in a room with high CO2 levels it gives  a good indication that the VOC levels are also high.

Going Forward

In the new house we plan to use controlled ventilation which will supply fresh air and in turn recover some of the heat blown out of the house .  It is a mechanical system called a Heat Recovery Ventilation Unit (HRV). I do not know why they don’t call it a fresh air unit as this factor has to be more important than recovering heat. In order for this fresh air supply system to work one has to control all drafts in the house as one does not want to be drawing air in around windows and doors and hope that the fresh air ends up in the correct room. This can only be achieved by eliminating drafts by sealing the building in an air tight membrane/system and blowing fresh air in and extracting stale air out using two ducts.

In order to carry out airtightness in a home one appears to have a few options -On a block house this is achieved by internal plastering (and some preparatory work) or for a wooden frame house one can use a membrane or take a chance on using OSB (Oriented Strand Board). Even a block house will still need air tight membranes on some structural details.

Another reason for using this special air tight system is to control moisture generated in the house from showers, cooking, drying clothes etc. This moisture can have a detrimental effect on the building fabric and reduce the insulation levels and in a worse case scenario lead to mould growth.  I feel the mould issue is going to be a health issue for generations to come where insulation is added ad hoc to dwellings without a proper design using building physics. I am not aware of any building physicists in Ireland guiding the construction industry. A worrying trend I am hearing of is cases where the consumer believed that adding insulation was a good thing not expecting the creation of mould and health issues for themselves.

The Airtight Target for a Passive house

In order to control the ventilation and heat loss the passive house standard requires less than 0.6 air changes per hour at their test pressure. The best analogy I could find for this figure was at the passivhaus.org.uk web site. One must achieve no holes or less than one 18 mm hole for every 5 m2 of the building envelope. 

Passive Haus
Airtight Standard Passive House

Practical Experience of the first steps in airtightness

As I was installing counter battens on the ceiling in front of the airtight membrane I know from experience I missed the rafters in 3 locations in the roof. I am using serrated nails with a nail air gun. Once these nails are fired they are almost impossible to remove.

Nails
Serrated Nails

The strategy is not to try and remove them as this would leave a hole other than a nail in a hole behind the batten.

Battens on Ceiling

Installing battens on the ceiling

Another factor is to ensure that the insulation does not sag below the rafters before the airtight membrane is installed.

When one is laying out the membrane one needs to work in a triangle when stapling. For example staple 3 metres  or more forward on one side and then find the centre of the other side and staple from this point to either side.  Ensure that stainless steel staples are used as there is very little in the price difference.

Self Build (Tools and Aids)

There are a few tools that I found very useful as a self builder (which are free).

One such tool is Evernote.  As self building involves plenty of research and the need to access information. This tool has proved invaluable for me to store information, share information, find information and make it accessible on a smart phone, any computer and automatically back up the information (nothing worse than loosing or not being able to find information). It also allows one to take pictures and have these stored in the same place.

All one needs to do is tag the information (a tag example could be the word insulation) -when you store the price/information you found on the internet about insulation it is stored with this tag and any other insulation data found over time. All pdf documents (these are usually research papers) can be stored also. There is an option to buy the premium version at €40 a year then the individual pdf content of the documents can be searched.

Another tool is Autodesk Design Review 2013. This tool allows you to open autocad files that your architect or engineer may have used for your build. It also allows you to edit these with your comments , take measurements of the drawing and draw simple shapes to highlight issues.

Another tool worth mentioning is Autodesk DWG Trueview. This is more similar to Autocad as it is mainly a viewer (allows one to open files).

THERM

A tool that allows one to calculate the heat loss of thermal bridges is Therm. It was developed by Lawrence Berkeley National Laboratory (LBNL) and again it is free. This tool will show you how cold (and the heat loss) your floor/window reveal etc is going to be near outside walls and the actual performance value so that the real heat loss can be calculated. (One can easily get a feel of the importance of this detail and the energy lost if you see mold/condensation around windows/doors etc ). This software will show graphically how much heat is lost (once calculated) and the temperature/heat loss you can expect on details such as window frames, door thresholds, the steel ties in your block work, the steel beam sitting on your inner wall  or foundation etc.

There are two parts to calculating the actual heat loss – the first is drawing the detail (fairly simple and involves time) and the other is the actual calculation (tricky I feel for a self builder). If one draws the detail this can save costs if a third party does the calculation for you).

Thermal Bridge
Thermal image of temperature changes in a foundation with low heat loss. The right hand side is the internal floor. The blue, purple and green colours are low temperatures. The green colour is 5 degrees Celsius.
Therm
The above foundation with no insulation. The inside floor has a high heat loss when the inside room temperature is 20 degrees Celsius. The small red line on the floor shows a wooden floor installed thus delaying the heat loss.

 SketchUP

This tool allows one to model in 3D your house design and carry out a walk through to get a feeling of the internal or external design. It also is used by the passive house institute on their energy balancing software PHPP so it is a worthwhile tool to learn.

Hardware

Other than a smart phone which is a real help when one wants to send/receive files, images or emails and keep things moving on site a device called the Samsung Note 10.1 (2014 Edition) makes documenting ideas and drawings a great resource while on the move. It is only one of a few devices that has a real pen and sketch pad that allows one I feel to replace a piece of paper because one can rest your palm on the screen like a piece of paper and write or draw.

Sun and Climate

Sun Surveyor Lite predicts and visualizes Sun, Sunrise and Sunset positions and times with a 3D Compass on your smart phone. It is useful in identifying the site layout and potential shading issues from trees etc. One can simulate the sun at different times of the year. If one want to do the exercise on paper then this web may be of help- http://www.gaisma.com/en/

Performance Standard -Setting the Standard

The passive house software allows one to set your own performance standard by selecting how much energy (oil/gas/electricity) one wants to use to heat the building.

For example current Irish house builds that comply with today’s standard 2014 are estimated to use 100watts per m2 (subjective). The passive house standard if one goes for certification uses 10w per m2 (objective).

The real benefit for using the PHPP software is that the performance approach can be set by the home user. For example if I want to reduce my energy consumption to 1.5 litres of oil per m2 of the house size then I can set the software to a maximum of 15kwh per m2 for the year while maintaining a temperature of 20 degrees Celsius.

In a typical 3 bedroom house with an area of 100m2 the oil usage would be 150 litres a year.  With the PHPP performance software one can set the number of litres of oil (or gas etc) per year that your residential or commercial property will use to within a small margin of error. In other words you select the performance value of your build.

In summary the PHPP software takes into account your comfort and health (temperature and oxygen levels)  by removing high CO2 levels and VOCs and providing an even temperature throughout the house.