How to turn a lovley old house with solid walls into a warm efficient home

AIR SOURCE HEAT PUMP - MECHANICAL VENTILATION & HEAT RECOVERY

SPACETHERM INTERNAL WALL INSULATION - UNDERFLOOR HEATING

WALL RENDERING

My concrete sub floors would need plenty of time to dry before I could do more work to the floors. I turned my attention to the end wall of the house. The south facing wall of the house takes all the weather. There was render on the south gable wall of the old part of the house, though this was only ever on the top two thirds of the wall. Itwas cracked and in shocking condition so I planned to have it re-rendered. Because, when building the extension, there was no perfect brick match I built the adjoining south wall of teh extension in concrete block. I would now have old and new rendered to look like one.

I also wanted to change the window arrangement, so had quite a bit of work to do before rendering could be done.

Blocked windowThe gable wall of the house had a centrally placed window. I intended to build a new fireplace on this wall so the window had to go. I liked gaining the light that came from the south elevation, so decided I would install two new smaller windows either side of where the new chimney breast and fireplace would be built.

I removed the window, blocked up the wall and marked the positions for the new windows.

Inner lintelsI cut out brickwork from the inside and fitted a lintel above each window location that was four inches deep, so only half the wall thickness. I then did the same from the outside so that the ful thickness of wall was supported.

By doing half the wall thickness at a time, fitting the lintel and allowing the mortar to set I managed to omit the need for using props.

Once all lintels had been in place for a while I set about cutting holes for the new windows.

You can hire machines that would cut right through the thickness of a 9" wall, but I was on a money saving trip, so used my standard 9" angle grinder and worked from both sides. Took a bit longer but I got there.

 

I had fitted concrete lintels below the windows of my extension so I did the same here. Unfortuantely, I could no longer find anyone making them so I took dimensions from the ones I had, made a mould from old bits of kitchen worktop and cast my own.

I fitted the new windows that I had bought at the same time as I built the extension.

You can see that I had also been up and removed the render from the end gable wall.

Window holeThe extension, to the right, was built using concrete block for this elevation as it would now all get rendered and mactch in.

With the windows fitted and wall prepared I was ready to have it rendered.

I made the decision not to render this wall myself. With the extension too, this is a large area and I felt that I didnlt have sufficient experience to be able to work fast enough to do a good job. This elevation is very visible within the village, so I really wanted it to look good.

Outer llntelsJust as important to me was the product used for the render. There are many options from traditional sand/cement, lime or a miriad of 'coatings'. In my earlier article on Wall insulation I raised my concerns about the potential for interstitial condensation. As this wall would be insulated internally, the coating I chose to use externally would have an effect on the wall's performance when it comes to vapour permeability.

Lime is considered 'breathable' so in essence it has the qualities I was looking for. However, never do I see this claim quantified. As always, I did plenty of research and found a French product called Parex. This is a render product that has a 'through colour' meaning that it's not painted later, and it won't peel. It was additives to allow for some flexibility and also water repellent properties. Crucially, they have data sheets available to back up their claim of 'breathability' with figures.

I supplied the data for inclusion in my WUFI analysis (see earlier article on Wall Insulation) so that the external wall covering could be modelled along with my plans for internal insulation. I am happy to say the system passed the WUFI test so I felt this render would give me good protection from the prevailing weather without compromising my vapour open approach to my insulation plans.

Windows fittedThough I worked off some dodgy scaffold towers when I built the extension I coudn't ask the same of a professional, so I hired scaffolding.

I chose a beige colour render. The product, Parex, comes in 25Kg bags and for a job of this size was applied by trowel, though for larger jobs it can be sprayed on.

Rendered wallMesh was first appplied to the old brickwork to prevent cracking. Beading was used at the edges as the render is only on this one elevation of the house.

I think it looks smart and have to say that Paul Holland (based in Gloucestershire if you're interested) did an utterly fantastic job.

 

 

 

 

 

 

 

 

 

 

 

 

 

© Christopher Thompson