Re: Bulding with SIFs
Yes, the system up front can is more expensive than a TF, but it is also considerably stronger (you can have conc screed on std panels, upstairs), much much quieter (party walls quieter than concrete, for example....) and closer to being finished than a TF (we can have conduits for elec, ventilation, hoover systems in internal panels), so yes, it can come back to you.
The roof in particular is the system's forté. You get a full sealed, insulated, strong and silent warm roof system, as standard. No cut timber (so no joints or waste), no wall plate to seal, no crawl spaces to seal. Dormers, usually a nighmare, are actually easier for us, and inherently better built than a cut roof. The easiest roof anyone will ever put solar panels on as well, that's for sure.
A builder down here is quoting from 86-109/sq ft, for a turn-key SIP house, finished with UFH, solar, hi performance glazing, tiled, kitchen, wooden floors, paths, treatment plant, paths, painted & decorated, drive and kerbing (chippings, not tarmac ! ). (iirc, that house had 14k kitchen, 25k plumbing/mech, 30k windows, so a good spec.) The variation the per sq ft price comes from the design of your build. The more complex, the more expensive (same as for everyone else). Inherently simpler designs are better value. Put the money in the performance, not the weirdness, that's my 0.02..........
Prices for our kit include all design, manufacture, delivery and erection charges, including the crane (fixed price), and we dont' use subbies.
Me, I think that's very reasonable considering the huge peformance you get. Put it this way, one of our houses was blower tested (in Co Meath inside the last two weeks. Without ANY plasterboard inside, no front or rear door (temp plywood ones, taped in), key joints taped, window opes taped to SIP frame, conc floor screed in, but no floor coverings, NO airtightness membrane - the test came in at 0.9m3/hr/m2. Now, remember, that's the performance inherent in our delivered panel. His assessor expects to achieve a further 20% upon finishing out (and fitting the doors !). That's pure passive house values.
Now, if you are self-building, I'm sure it would come in cheaper finished per sq ft, but some things do greatly distort the price of houses, sometimes. Huge mega-expensive kitchens, or tiles, even heating systems. (I see people spending 30/40/50k all the time.....). Practically, those houses are way over-heated.....one, near us, has UFH up and down (conc floors on GF and FF), open fire, solar AND geo. In a 2.5k sq ft house ?
Self-build would also have the advantage of having a lot of the 'big stuff' sorted, so if you are into DIY-ing your build, at least you can do the 'interesting' or 'nice' jobs, and details (which a lot of self builders are more interested in.)
What's not to like ?
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