House with solid brick walls and external insulation

FreeBear

RHemmings said:

FreeBear said:

A couple of shots of the stairwell.

There are a few details hidden from view, so if/when you are ready to undertake insulating walls, feel free to ask.

Thanks for the photos. Very interesting to see. 

Further up this thread I mentioned a house where I believe they are going to be adding external insulation. I passed by it today. I'm going to be keeping an eye on this. Given that I saw it a week ago I thought they might have progressed a lot by today, but no. It looks about the same. 

Oh dear. Poor house..... It has been rendered (probably with cement or K-Rend), has had the damp wallies injecting their magical chemicals in to the base of the walls, and is now getting encased in polystyrene. The owners will be having the damp experts salesmen back in a few years time for more "treatments".

Solid brick walls (certainly on the ground floor), need appropriate materials used to maintain breathability - Typically, cork or woodfibre with a lime render. If you are using impermeable materials such as XPS or PIR, a ventilated air gap is needed (which reduces the effectiveness of the insulation).

I can get away with using Celotex on my solid brick wall as it is only the upper half of the property, and it has a cement render on the outside (done when the house was built).

RHemmings

I'm still a believer in insulation even after my viewing 'failure' with the house I viewed yesterday. However, it has been made abundantly clear to me that ventilation has to be taken very seriously. 

I'm not aware of the problems of putting insulation over the top of existing rendering, etc. I'll continue learning about these issues. 

FreeBear said:

Oh dear. Poor house..... It has been rendered (probably with cement or K-Rend), has had the damp wallies injecting their magical chemicals in to the base of the walls, and is now getting encased in polystyrene. The owners will be having the damp experts salesmen back in a few years time for more "treatments".

Solid brick walls (certainly on the ground floor), need appropriate materials used to maintain breathability - Typically, cork or woodfibre with a lime render. If you are using impermeable materials such as XPS or PIR, a ventilated air gap is needed (which reduces the effectiveness of the insulation).

I can get away with using Celotex on my solid brick wall as it is only the upper half of the property, and it has a cement render on the outside (done when the house was built).

For complicated reasons (oh all right, my adult son has had bad experiences and is very sensitive to black mould), I'm looking into active heat exchange ventilation for houses. 

I've heard about 'injected damp course', and was wondering what that was. Is this what you mean by 'damp wallies injecting their magical chemicals'? 

Netexporter

Have a look at the AECB website The AECB is the home of low energy, sustainable building to get an idea of the different systems available. You will discover that retro-fit insulation is a complex subject, with many variables to overcome, that requires great attention to detail.

MVHR is an excellent (essential?) addition to a well insulated and air-tight home, especially if you can cover the overall power consumption from solar and batteries. However, it won't be easy to retro-fit in a multi-storey home. Bungalows are your friend, in that respect.

Gerry1

Netexporter said:

Bungalows are your friend, in that respect.

But probably not in other respects unless one is needed for mobility reasons or it's fantastic in other ways.  They're not usually money saving because of higher heat losses from the larger roof area, and the purchase price is usually higher.

Netexporter

I wasn't suggesting bungalows are a panacea. I was using that style of dwelling to illustrate the difficulty of retrofitting MVHR on the lower floors of multi-storey dwellings. You are likely to have to take down and replace a lot of the ceilings and probably have to use sub-optimal ducting, in terms of cross-section and radius of bends, that will have detrimental impacts in terms of noise and energy requirements.

FreeBear

RHemmings said: I've heard about 'injected damp course', and was wondering what that was. Is this what you mean by 'damp wallies injecting their magical chemicals'? 

"Damp wallies" is a term I picked up from the Heritage House web site. A chemical injected DPC is just one of the products sold  by these damp proofing companies - Contrary to their claims, the effectiveness of the work is debatable. Much of the time, it is the waterproof render/plaster that they slap on the walls internally that masks the problems for a few years.

RHemmings

I was out of my city all day today, and I'm way behind on conversations here. 

For me part of what would make a bungalow an attractive option is the limited internal space that needs to be heated. And, that it's easier to install a centralised heat exchange ventilation system in a bungalow that has a loft. Both of these beliefs could be changed by sufficient argument. 

The bungalows I've seen also seem to have roofs that to me appear to be suitable for solar cells. One property that I would quite likely buy if I had an extra £20-30K has a detached garage with a nice looking roof on it and I think that could have panels on it too. 

There are some non-energy reasons that attract me to bungalows too. E.g. if I stay in the house into old age, then I don't have the 'stairs' problem that my mother had into her 90s. 

But, I'm not limiting myself to bungalows. 

Thanks for the explanation about 'Damp Wallies'. Clearly there's more I need to learn here. 

I didn't know the acronym MVHR, but I knew what they were. The acronym will be very useful for me as it's extremely likely I will install these. 

markin

You don't know if that house had cracked render and damp problems first and the new EWI and render was the cure, but that obviously also traps the water in and needs drying out and treating.

RHemmings

markin said:

You don't know if that house had cracked render and damp problems first and the new EWI and render was the cure, but that obviously also traps the water in and needs drying out and treating.

The EWI was done a fair while ago as the EPC that mentions it (out of three) is expiring next year. I think that Occam's Razor suggests that the EWI is causing the current damp problems. 

markin

Can you see extractor fans in the kitchen and bathroom, or a tumble dryer? Some times it is just the people that live there never open windows and use rads to dry washing.

Most houses can be fixed.

I think the roof vents are simply called tile vents as they replace a tile