woodfibre v mineral wool v something else

[redtop]

so we have a stick build specified, with vapour proof OSB on the inside pavaflex between studs and pavatherm as external wrapping. then battons & cladding. Went for this as like the breathability and high thermal mass and natural materials.  Also lack of membrames appeals to me.  Anywhooo; surprise surprise, foundations and steel substructure costing more than expected so looking for possible alternatives. We do want to stay with natural materials and I have worry about fire rating (raised wooden house in a wood with crap fire engine access) and want a building fabric as high spec and robust as my limited budget will allow.  Note the timber frame is slightly heavier than normal, C24 150 X 50 mm.  Wall thickness isn't an issue as no neighboures near by.  Driven wind and rain is as we are in Looe near the sea. Advice welcome ? 

[Simplysimon]

20 minutes ago, redtop said:

 high thermal mass , C24 150 X 50 mm.   Advice welcome ? 

don't mention the first again, no, no, you haven't found out why yet? ?, the second, isn't that standard sectional size? advice, for now, given. drawing for steels and founds would be appreciated to see why so expensive unless already posted?

[ProDave]

Our build sound similar, except 195mm frame. 100mm wood fibre on the outside then render.  The frame insulation was originally going to be blown in wood fibre.  when the budget got tight we changed to Frametherm 35 insulation in the frame. Hardly any difference in insulation value but a lot cheaper mainly due to being a DIY job vs employing a team with the machine to blow the other stuff in.

 

The building is performing very well, heat loss (not much) matches the calculations, very low heating costs and very long decrement delay.

[redtop]

foundations are 41 odex piles driven 5M into the rock, each one is 220mm wide. And price has gone up as grounnd workers have had to come back and help dig out piling machine... re the timber we could have used C16 100x37 (or something like)

[redtop]

3 minutes ago, ProDave said:

Our build sound similar, except 195mm frame. 100mm wood fibre on the outside then render.  The frame insulation was originally going to be blown in wood fibre.  when the budget got tight we changed to Frametherm 35 insulation in the frame. Hardly any difference in insulation value but a lot cheaper mainly due to being a DIY job vs employing a team with the machine to blow the other stuff in.

 

The building is performing very well, heat loss (not much) matches the calculations, very low heating costs and very long decrement delay.

we had planned on 160mm for the outside, and given we are in cornwal its not cold (wet yes...). maybe we drop to 100mm.  quote for external and between the studs insulation currently at 11.5K, that includes vapour wrap and (very expensive) fastenings for the external boards.  it doesn't include floor and roof insulation 

[redtop]

and here is a some man porn (sorry ladies, but well, its big and makes a loud noise)

 

[ProDave]

6 minutes ago, redtop said:

we had planned on 160mm for the outside, and given we are in cornwal its not cold (wet yes...). maybe we drop to 100mm.  quote for external and between the studs insulation currently at 11.5K, that includes vapour wrap and (very expensive) fastenings for the external boards.  it doesn't include floor and roof insulation 

I forget the price of the wood fibre cladding (It was not itemised on the invoices) but the Frametherm to insulate the whole house, floor walls and roof was about £3K  so your insulation figure sounds high.

 

Air tightness membrane, (Protect Bariair) cost less than £400

 

External wood fibre fixed to the frame with a lot of 150mm long screws with big plastic round things to hols them on, not very expensive.

 

I presume your prices includes fitting? (I did all mine myself)

[redtop]

2 minutes ago, ProDave said:

I forget the price of the wood fibre cladding (It was not itemised on the invoices) but the Frametherm to insulate the whole house, floor walls and roof was about £3K  so your insulation figure sounds high.

 

Air tightness membrane, (Protect Bariair) cost less than £400

 

External wood fibre fixed to the frame with a lot of 150mm long screws with big plastic round things to hols them on, not very expensive.

 

I presume your prices includes fitting? (I did all mine myself)

no that was supply only, 190m2 of external walls so not massive

[redtop]

quote below (ex VAT) and some bits removed for clarity (minor stuff like tape). I mean £800 for fixings!

 

• 190m² Insulation timber frame, Pavaflex 140mm @ 375
• Isolair 140mm (replacement for Pavatherm Plus (discontinued)

 

1. 192.000 140mm x 1780 x 560 Isolair (Pavatherm Combi) T&G 4,869.12 
2. 20.000 220mm Topix Timber/CLT Fixings (Pack 100) 800.00
3. 3.000 1.5 m x 50 m Pavatex ADB Membrane (70 m²) 414.00 
4. 94.000 140mm x 375 x 1220 Pavaflex (1.83m²/pk)  2,336.84 
5. 2.000 Transport - 2 x 18t dedicated load 1,180

[Joanna Susskind]

On 12/11/2019 at 20:59, ProDave said:

Our build sound similar, except 195mm frame. 100mm wood fibre on the outside then render.  The frame insulation was originally going to be blown in wood fibre.  when the budget got tight we changed to Frametherm 35 insulation in the frame. Hardly any difference in insulation value but a lot cheaper mainly due to being a DIY job vs employing a team with the machine to blow the other stuff in.

 

The building is performing very well, heat loss (not much) matches the calculations, very low heating costs and very long decrement delay.

Hey Dave, where did you buy the Frametherm? Also where were you planning to source the Pavatherm? Thanks!

[ProDave]

I just phoned all the merchants and SIG (Sheffield Insulation Group) were by some way the cheapest for Frametherm 35 and they delivered with their own lorries.  But just because they were cheapest 3 years ago does not mean they will still be the cheapest.

 

All the wood fibre for my build came via a local builder but I don't think retail is their normal model. In any event they went into liquidation afterwards and have since been swallowed up by another larger local builder, so unlikely to help you unless you are close by here.