Old suspended flooring

[dabomb3k]

When I first moved into my
House I had a few problems with wet and dry rot due to poor air flor underneath my suspended timber flooring (downstairs) I had it all treated, new airblocks put in etc and it's been okay since,

I'm now looking to renovate my living room and as such will be pulling the floorboards up to retrofit insulation, the suspension underneath is approx 3 feet so no by no means small, I'm wondering if there would be any benefit down the line in rendering with waterproofs mixed in over the very old stone wall foundations or if there's an alternative method I could use to just make sure I make it as safe as possible,

I'm assuming when I pull it all up with the now adequate air blocks and the joists treated then the problem won't have come back but previously I had it all starting to climb up the walls etc and want to do everything I can to prevent?

Would a dpm to maybe the underside of joists be another option or something else you could advise??

The current plan is to lay insulation between joists, staple a Dpm sheet to that and then either relay floorboard or use p5 board before carpeting..

Thanks for any advice, novice on this subject

 

[tomfe]

Drape scaffold netting over the whole floor to support the fiber glass. You wont need a vlc as glass wool in vapor permeable but for belt and braces you could add a dpm over the joists.
You don't need to render under the floor it would make things worse if done in opc render.
You have adequate ventilation under the floor then everything will be fine.

An alternative is to pump the whole space under the floor with eps beads but as your void is large it would not be cost effective.

 

[noseall]

An alternative is to pump the whole space under the floor with eps beads

How does air circulation work when using this method?

 

[theprinceofdarkness]

The beads have air spaces within their mass. They will also stop so much water evaporating from the underfloor earth, by keeping it cool. I would just leave the under floor void alone. Glass fibre on netting will slow heat loss but allow moisture transfer. I would not mix a DPC in with a wooden floor unless you have done some serious calculations to prove condensation will not occur. Beyond my pay grade
Frank

 

[tomfe]

How does air circulation work when using this method?

You need ventilation under a suspended floor to remove stagnant air and condensation.
You have removed the need for any ventilation by:
Cutting out the stagnant air, there are is no space for it.
Cutting out any interstitial condensation by insulating with such a high thickness of product. If any condensation does occur it will be well within the eps layer so wont damage anything.

I would not mix a DPC in with a wooden floor

I am not sure I agree with this, all you are doing is adding a vapour check the same you do with a timber frame with osb on the inside.

 

[theprinceofdarkness]

I thought the VCL was over the wood and under the plasterboard, so allowing any moisture to evaporate through it. Also the timber frame is highly insulated from the outside so both sides of the VCL would be at the same temperature. This is not the same as under a dresser pushed up against an outside wall. So the air under it could be at the outside temperature.
Frank

 

[tomfe]

Water does not pass through a vcl, that's the whole purpose for it.
It keeps the warm damp air from condensating in the fabric of the building when it hits the dew point.
You are thinking of a breathable membrain you put in the outerside of an insulated building.

Regarding a floor, just think of it like a warm roof but you are standing on the ceiling.