retrofit of small concrete block building

[Anonymous]

Hi there,
I have a 30m2 concrete block building currently used for storage. I want to make it into a pleasant, self-contained unit. I really want to use natural, low embodied energy products, and NOT plasterboard etc. Is this possible? Can these products be compatible with each other? If so, please could you recommend the best way to proceed and/or the best products for the job.
Many thanks,
Tom

[Geoff Stow]

Wow thats a question and a half. I would think that if you want to change it from a storage unit to a residence you will have to apply for change of use and it will have to comply with current building regs. Being that small it will be difficult to get the required levels of insulation. Assuming it is a single skin concrete building you could build an internal stud wall with insulation and then line it with something (plasterboard would be the easiest and cheapest as well as giving fire protection). I would not risk any insulation that would conduct moisture from the wall to the interior. This would mean loosing about 160mm on all external walls which is a good bit on such a small building. If you were prepared to look at some of the rigid foam sheet insulations they could be thinner they have high embodied energy but will save vastly more over the buildings life. If the roof has a large overhang you could build an external stud wall and insulate that and clad it in timber which may look better. You could then render the interior, But as I say this will only work if the roof has a big enough overhang to cover the new wall. The roof will have to be insulated. And think about a small heat source.
You will almost certainly have to change the doors and windows.
It may be worth checking the figures to see if it makes more sense to build a new building depending the quality of the existing structure.

[Anonymous]

Thanks Alan and Geoff for your replies. I think from the advice I have got from other sources aswell, that it's all pointing to using rigid foam boards to minimise the loss of space, but also because we will have to use it in the floor and (horror of horrors…) on the flat roof. A compromise on the idealism I started with but I do feel a demolition/start again is going a bit far. I may live to regret saying that when it takes months to complete!
I dare say we won't be achieving gold standard/passivhaus results here, but what thickness of foam do you think would be sensible here? And by the way, we WILL be changing the doors and windows!! I was laughing because if you could only see the old ones you might have a little chuckle to yourself. I believe they were a good century old even when the building was constructed 40-odd years ago! Which brings me to another question…. would this situation merit considering the use of triple glazing or is that overkill on such a small project pf this kind? We will just have a small woodburner for heating and the water is on gas off the mains from the house.

[Anonymous]

whoops, pressed the post button by mistake, anyway just to say that any info re all this much appreciated.

Many thanks,

Tom

[Nick Grant]

Tom I think you should go with Alan's advice but whatever you do you should not need a stove in a 30m2 insulated building if you have gas then the heat loss from a hot water cylinder plus other gains will almost heat it and you will save the space for stove and wood storage.

Triple glazing can be had for similar price to double from some suppliers and has the advantage of almost no condensation risk and freedom to use more glazing area.

However if you are just cobbling this all together with no budget then yes it will be overkill.

Nick

[Author]

Posts