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Jaded Burnout
Jul 10, 2004




CancerCakes posted:

Sounds positive anyway, good job. Are you going fully flat roof or monopitch?

The latter, I think.

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Jaded Burnout
Jul 10, 2004




What options do we have for flat roofs these days? Assuming not 90s tar style, it's what, rubber, fibreglass, anything else?

CancerCakes
Jan 10, 2006


I think most will do epdm on OSB or similar. We don't really get felt tiles like in the us, but considering the horror stories in the construction thread that is for the best. I suppose you *could* slate it but the expense and extra weight is up to you.

I came across this site, seems pretty good for insulation:
https://www.secondsandco.co.uk/kingspanshop

iv46vi
Apr 2, 2010


Jaded Burnout posted:

What options do we have for flat roofs these days? Assuming not 90s tar style, it's what, rubber, fibreglass, anything else?

On residential side of things you now see SIPs and green roofs.

Jaded Burnout
Jul 10, 2004




CancerCakes posted:

I think most will do epdm on OSB or similar. We don't really get felt tiles like in the us, but considering the horror stories in the construction thread that is for the best. I suppose you *could* slate it but the expense and extra weight is up to you.

I came across this site, seems pretty good for insulation:
https://www.secondsandco.co.uk/kingspanshop

Noted, thanks.

iv46vi posted:

On residential side of things you now see SIPs and green roofs.

I was just looking at green roofs. It looks like they're relatively affordable to buy as kits, but in any case they go on top of a normal waterproofing system, but it would e.g. mean that an EPDM roof would be more puncture resistant.

They are heavy, though, like 75kg/sqm, so it would require some really beefy joists, like 3x8s at 400mm centers (for the 5m open span I have to cover).

So, maybe a £200 price difference in materials to support the weight. Not too bad.

cakesmith handyman
Jul 22, 2007

Pip-Pip old chap! Last one in is a rotten egg what what.



EPDM is king for ease/time of install, there are companies offering 50 year warranties on their thicker products. It's pretty trivial to patch damage (with the correct materials/glues). I don't know enough about green roofs to offer anything other than the opinion "I think they're nice"

Jaded Burnout
Jul 10, 2004




I've done some research and I'm going for EPDM. The builder preferred fibreglass because it's less of a pain to flash in the skylights, and I agree with him on that, but fibreglass is a real dick to work with *after* it's installed, which matters more to me (see previous adventures in skylights).

So I'm going to tell him I'll build and install the upstands and install the skylights (with lifting help this time) and that should remove a hassle point on his side (and I get to make sure it's done right first time this time).

wooger
Apr 16, 2005

YOU RESENT?

Jaded Burnout posted:

They are heavy, though, like 75kg/sqm, so it would require some really beefy joists, like 3x8s at 400mm centers (for the 5m open span I have to cover).

This can’t be right can it, how thick does the soil / substrate need to be?

I wouldn’t expect even a foot deep sq metre of compost to weigh 75kg.

Jaded Burnout
Jul 10, 2004




wooger posted:

This can’t be right can it, how thick does the soil / substrate need to be?

I wouldn’t expect even a foot deep sq metre of compost to weigh 75kg.

I think it's the water as much as anything.
https://www.ansgroupglobal.com/green-roof/technical/my-building-strong-enough-green-roof

Just Winging It
Jan 19, 2012

The buck stops at my ass


The volume of a foot deep, square meter cube is about 300L, so 75kg feels on the low side for that much material. If it was solely water it'd weigh around 300kg.

Jaded Burnout
Jul 10, 2004




Yeah I can't speak to the density of compost, but I know damp soil is real heavy.

Here's my latest comms to the builder, I'll probably get on to the nitty gritty later today.

JB over email posted:

I'm going to have to take some measurements to come back with a really accurate spec, but the summary is we're going to stick with the original plan up to the finished floor level, then stick build above that. I've gone over the engineer's calculations and it's not safe to have heavy machinery on normal timber floors; the usual planned load is 0.75kN/sqm, and we need to support more like 5kN/sqm (which the block & beam supports).

I'd like EPDM for the roof because fibreglass is such a bastard to work with for repairs etc down the line. I acknowledge this makes the skylights harder during initial install, so if you frame the openings and fit a single flat sheet of EPDM I'll then build, install, and flash the kerb upstands afterwards, and install the skylights (with some lifting help from your crew).

I've looked over the span tables for the roof and we're looking at something like 3x8 joists at 400 centres, doubled up for the skylight openings (and trimmers). I'll get you more detail on that too.

Other than that, the superstructure will just be the framing, roof, and outer sheathing/wrap for the walls. Insides left open and uninsulated, I'll deal with that myself after. Likewise with external cladding and battening not needed. Supply and fitting of the (non-skylight) doors and windows would also be great, though I can arrange that elsewhere if necessary. No trenching or soakaway work needed, I'll integrate that into the followup work with the landscapers. Having standard guttering leading to a drainpipe with a shoe should be sufficient for now.

NotJustANumber99
Feb 15, 2012



lol the insulation I had priced up like a year ago at 30quid a sheet is now £100! kill me

Jaded Burnout
Jul 10, 2004




I'm concerned enough about pushing the edge of pre-defined span tables etc that I'm going to have the structural engineer take another pass at the new design.

I need to redraw a bunch of the elevations in at least a basic way, and checking the openings, piers etc are still safe is beyond my ability, but I'm comfortable enough that we'll fit everything in, and the SEng can do the rest.

Jaded Burnout
Jul 10, 2004




New sketch (with copious notes) sent to the engineer.

NotJustANumber99
Feb 15, 2012



I'm glad you labelled the concrete

also do you have beam and block floor beams inside the wall? I think that isnt how it would be. save on a couple of beams

be like one of these:

NotJustANumber99 fucked around with this message at 20:55 on Apr 17, 2021

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Jaded Burnout
Jul 10, 2004




NotJustANumber99 posted:

I'm glad you labelled the concrete

Everything gets a label. No ambiguity. Ambiguity leads to misunderstanding. Misunderstanding leads to me having to redo something in a year.

NotJustANumber99 posted:

also do you have beam and block floor beams inside the wall? I think that isnt how it would be. save on a couple of beams

be like one of these:



I was following the engineer's drawings:

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