Clc136a

Yes, plan is to bring the loft within the thermal envelope to avoid extremes, even for storage. Not full-fill on the rafters ( only 140/175mm) to allow air circulation above and to ridge. Question was on choice of product and what R number I can realistically aim for? Thanks

Hi all, after a bit of expert advice on this please? 1980s house with concrete tiles and what looks to be impermeable felting, 175mm rafters spaced roughly 30-35cm x 32. Insect proof venting at eaves but currently only about 200mm fibreglass ceiling roll insulation. Thinking to install either 400mm omnifit or flexi slab 140mm flush to front rafter face to leave gap behind. U=0.035-8. Venting baffles at eaves. The rafter length is about 4.5m but thinking to install 3 x 1.2m slabs on each and close over below the ridge. Next would be either directly insulated plasterboard across the rafters (moisture barrier?) or more complicated battened superfoil type product. What insulation number could I expect from this approach and would it work to upgrade a cold loft to a better performing one? many thanks, Chris

Also interested in building in ICF, walk out semi basement into clay bank, 3 units. Considering Jakon, but struggling to find SEs or builders near Gloucester experienced (sure they're out there?) Given that part of the basement will form a terrace and support some weight is horizontal ICF recommended?

A few hundred meters away, a few years ago, a self builder (and by trade) excavated about 6m at about 80 degrees! With gardens above! FORTUNATELY, it was a dry summer and it stayed a looming bank whilst the triple skin wall was built and water proofed. Professional advisors will (I think rightly) not let you do this any more.

Yes, piling doesn’t come cheap but once you’ve got a slope and suspect ground it’s safe and CFA is quick I’ve been told. You can get an indication of the slope from the attached (not wedded to the layout). @Wumpus what temporary works did you need to excavate and build retaining wall? In our case the ground doesn’t flatten until 62m so a way above the top of our ground floor retaining wall 58m. @tonyshouse thinking by talking to different specialist contractors you home in on best way of doing things. Thanks for your ideas

Thanks for your comments. I have spoken to a few local SEs but none appear to have experience with insulated rafts or ICF so far… Regarding retaining wall, the soil survey did suggest slip planes are a possibility and CFA retaining wall would pin that, plus it eases waterproofing issues and it would mean house piles are only taking vertical loading I think?

Hello experienced folks. I’m a complete novice looking for opinions on the best construction for a highly insulated 175m2 of simple form. Site is sloping downwards towards the front of the house from where it is pretty flat, hence semi/walkout basement to the frontage. 4-5m in front and parallel is a main sewer at 4-5m depth, so I think the front of the house (at least) should be piled. In addition soil survey shows lias clay. A couple of piling contractors have suggested CFA retaining wall across the back although a temporary works co would like to hire me trench sheeting. Once the footprint has been excavated I think the piling company could probably put in 8 piles and connect a ring beam. Does it make sense to then use an insulated raft and ICF system like Jakon? Need to find a local (Glos) SE with experience? Obviously TF doesn’t make sense in this location and I am persuaded by the thermal mass argument with exterior insulation. it has been suggested to use old fashioned shuttered insitu concrete and attach EPS afterward? Grateful for any comments, thanks

Hello all! First time posting on build hub but I’ve been reading with interest on lots of topics! We’re planning an into-the-bank 230m2 warm roof L gable design and trying to tap into as many sources of experience as possible... Its lias brown clay from the soil survey in a garden plot and originally we’d assumed contiguous pile wall and piled foundations and beam and block and cavity wall - architects idea... Latterly I’m pretty convinced (subject to SE report) after conversing with the basement expert the best and cheapest way is a waterproof cast in situ semi basement with external insulation. I was thinking foam glass aggregate, particularly under slab as it’s free draining, but transport from Germany means it is both costly and has a higher carbon footprint than EPS so I’m swayed towards a reinforced raft like kore and drain around the perimeter. We’d then have starter bars and then cast waterproof walls for the 2.5m into the bank, then maybe 600mm EPS blocks wrapping the walls before drainage membrane and backfill. I have modelled it in PHPP and had a certified passivhaus consultant check the numbers. Some of the elevations are timber clad, others ‘were’ stone facade but might change to something less complicated for external insulation model. I’ve talked to Optiwin about windows and doors, any comments? And a few Velux quin roof windows. Very interested to hear peoples comments and suggestions. Think we’re ok with the internal layouts but might post later on this. Thanks, Chris