Thedreamer

I'm getting a floor

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I'm thinking about the first layer of the sub flooring material on top of the joists.

 

Which would be the best choice out of these three?

 

18mm T&G OSB

18mm T&G Chipboard

18mm Plywood

 

Our suspended timberfloor will be made up of the following: 60mm Quinn therm (foamed to ensure tight fit) and 90mm Frametherm 32 sitting within the joists. One of three options above, followed by 25mm Quinn therm (taped and seamed) then 22mm Chipboard, then underlay followed by finished floor which will mostly be solid oak or carpet.

 

 

 

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Have you looked at real life examples to see the amount of movement there will be with that quinn therm sandwich?

 

I imagine it might limit your choice to carpet.

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150mm joists?  That sounds rather thin. Ours are 300mm JJI's

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I think chipboard may be cheapest.  Sealing all the edges will be good. @ProDave I think this is  a ground floor with sleeper wall supports.

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6 minutes ago, Mr Punter said:

. @ProDave I think this is  a ground floor with sleeper wall supports.

Could be. But I never saw the point in doing that.

 

When I was doing the spec for my house one thing I wanted was simple foundations, i.e specifically no sleeper walls to add to the number of trenches and ground work.  If the first floor joists can span that gap, then so can the ground floor joists.  That of course meant thicker joists, which meant I could get enough insulation within the width of the joists so no adding extra above them.

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10 hours ago, Thedreamer said:

I'm thinking about the first layer of the sub flooring material on top of the joists.

 

Which would be the best choice out of these three?

 

18mm T&G OSB

18mm T&G Chipboard

18mm Plywood

 

Our suspended timberfloor will be made up of the following: 60mm Quinn therm (foamed to ensure tight fit) and 90mm Frametherm 32 sitting within the joists. One of three options above, followed by 25mm Quinn therm (taped and seamed) then 22mm Chipboard, then underlay followed by finished floor which will mostly be solid oak or carpet.

In terms of strength Plywood would be the strongest but is by far the most expensive. The next strongest is 18mm T&G OSB with chipboard the weakest but slightly cheaper than OSB. Now if you're joists are at 600mm centres you'll need 22mm T&G Chipboard but 18mm thickness is fine for the other options at 600mm.

 

Is the 22mm chipboard on top of the 25mm insulation screw fixed through the insulation to below or floating? Not sure if you know but you should put in a 25mm batten (same thickness of insulation under all doors as this is where it compresses the most. 

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first layer what ever you choose needs glue +as well as fixings to increase strength and cut down on squeaking.

my choice  22mm t+g  chipboard 

your design should state what thickness to match up with joist spacing and joist sizes.#

everybody is guessing  including me

as i see  no REAL definative spec on joists -150mmdeep    but how thick+  what type+ what span  ?

 

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Thanks for the comments.

 

Yes we have 5 sleeper walls supporting the joists at 400 centres.

 

Looks like chipboard might be the way to go on the subfloor.

 

I'll need to check the specification on the top chipboard layer i.e fixings

 

 

 

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@ProDave See for your ground floor, how did you achieve the requirement for a continuous layer of insulation at some point in the make-up to minimise cold bridging?

 

Maybe I've misunderstood the requirement here?

 

 

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3 minutes ago, Thedreamer said:

@ProDave See for your ground floor, how did you achieve the requirement for a continuous layer of insulation at some point in the make-up to minimise cold bridging?

 

Maybe I've misunderstood the requirement here?

 

 

Used JJI I beam joists, I think that solves the cold bridging issue.  All I know is it passed SAP and building control.

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5 hours ago, Thedreamer said:

Looks like chipboard might be the way to go on the subfloor.

 

I would agree, used the chipboard flooring and ply flooring sheets in two different projects and much prefer the chipboard. 

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Been doing some thinking over the weekend. The quinn therm sandwich is now gone.

 

New make up 22mm Chipboard, 6mm Natura Sonic Gold underlay, 18mm Engineered oak.

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10 hours ago, Thedreamer said:

Been doing some thinking over the weekend. The quinn therm sandwich is now gone.

 

New make up 22mm Chipboard, 6mm Natura Sonic Gold underlay, 18mm Engineered oak.

So how does that get you enough insulation?

 

Any access underneath to over span underneath the joists with Quin therm?

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4 hours ago, ProDave said:

So how does that get you enough insulation?

 

Any access underneath to over span underneath the joists with Quin therm?

 I think generally you always want to leave the timber at the bottom of the joists exposed so enable air circulation. I'm still going to have 150mm insulation between the joists which will be sufficient.

 

 

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that what air bricks are for to ventilate under floor 

sealing under joists will improve insulation dramatically --trapped air is best insulation you can get 

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9 hours ago, scottishjohn said:

that what air bricks are for to ventilate under floor 

sealing under joists will improve insulation dramatically --trapped air is best insulation you can get 

 

What air would you be trapping, the joists are already filled with insulation.

 

The air below would be cold. 

 

 

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