Gary Martin

Thanks Rick. Russell your comments have certainly given me a pause for thought.

Not sure if porotherm clay blocks would class as non standard construction or not. easy saleable construction is important to me.

Iceverge thanks for your answers. yes I meant a cavity wall made with concrete blocks, (I said I was new to all this). I take on board your advice re the battens etc. what do you think of initially only minimal fixings for the horizontal battens, then concrete screws in pre drilled holes, going through both vertical and horizontal battens to hold the whole thing together ? any internal walls will be timber studs so no cold bridging at junctions. for Johnmo, of course I am not aiming or planning or hoping for a bad build, by design or construction and would like perfection. I doubt the other timber framed owners wanted the problems they got either.

The whole thing was badly designed and built. The exposed glulam ridge beam was rotten on the ends too, In a coastal environment . my point is even a badly built block building can’t rot. Hence my preference for block over timber frame.

Jilly I meant arbitrary as in inside the cavity or outside it, in the room.

Thanks Iceverge my proposal was two skins of normal dense concrete blocks, not soft cavity blocks. the battens and counter battens would be 25 x50 not 38 x50 the vertical battens would have to be drilled and plugged the horizontal ones screwed to the others with 50 mm wood screws. ( vertical cladding) I agree extra work is required fixing the internal insulation boards, longer screws etc, but time would be saved on not messing around cutting the boards to fit in the cavity, around wall ties etc. Also no chasing out for cables and pipes, plus making good, as with a wet plaster finish. I still want to go cavity block built, not ICF or timber frame. my builder has just sent me pics of a 15 year old TF building that had a failed rainwater downpipe that had been leaking and splashing up under the cladding ,unseen for quite a while. The rot had gone from the sole plate to two verticals . He was brought in for minor alterations and it has progressed to a major refurb. not his original build by the way.

Thanks for your comments guys. timber or cement board or Plastic timber effect cladding was stipulated by planning to give an “ agricultural feel” to the build. It is replacing a Part Q permitted development. “ cladding boards “ was the term used. I know planning dept shouldn’t dictate like that but it’s where we are. please no further comment on cladding. Im now 100% fixed on cavity block construction, but not really convinced why internal insulation is not better. Any internal walls will be stud, so no cold bridging. Wall thickness won’t be any different to conventional as the cavity will be reduced by the same amount 100mm? As the internal walls will be increased. I realise that “ I pays my money, and I makes my choice, and have to live with it” but am genuinely hoping to learn from your collective wisdom. is it “ That’s just the way it is. Some things will never change” ( Credit Bruce Hornsby ) or are there more concrete reasons ?

150 sq mt dormer bungalow. was looking at timber frame as faster warm up and air tight. Heard of some with rot in base after a few years. ( I know it shouldn’t but it did ) I then considered cavity block for longevity but a slower warm up and difficult to get air tight. as insulation is essentially “inside” with TF, but “outside, in the cavity” with block, I thought it made sense to get the best of both methods. my plan, from outside in = timber cladding, batten& counter batten ( gives 50 mm air gap ) breather membrane, block, 50 mm cavity,block, 100 mm celotex, air Barr membrane, battens fixed through to blocks, plasterboard and skim. I looked at SIPS and ICFs but the “ none standard construction “ label makes mortgage or resale more difficult. I assumed the cavity block bit would be classed as standard construction and the siting of the insulation arbitrary. ??????

Up date on my supply. western power put a new pole on my land, and ran a cable to it from the neighbours pole. 70 meters WP sorted out the wayleave. they supplied ducting and a meter box. I had to dig a trench, place the ducting, plus drawstring, and fix meter box for temporary supply. They then ran cable from the new pole, underground for 20 meters and connected to the new box. £ 7,000

Thanks G&J. Could you expand please? I’m new to self building and keen to learn. thanks

Cavity for weather protection. Surely if insulation is held tighter against internal skin, there is no gap to slow condensation, also the celotex acts as a secondary vapour barrier to supplement a fully sealed one. any moisture in the blocks could dry out via the ventilated cavity. ? ps MVHR system will also be fitted. thanks for your comments gary

Just received PP to demolish a part Q agricultural building and build a smallish bungalow. In Cornwall im still debating construction methods. Any suggestions? got electricity for £10k and water for £10 k septic tank planned for sewage. gary

Could I build a new house with 50 mm uninsulated cavity block walls, with, say, 100 mm of celotex/ kingspan fixed to the inside walls, then service battens,vapour barrier, plasterboard and skim. would it pass building regs ?