Suspended Floors - Flooring options

Mumha

I'm unsure where to go with this. I know I will be putting an airtightness membrane on the floor first, but then what options do I have ? I'm thinking a good quality laminate, on top of an underlay, but if the underlay is too thick, won't this cause a certain amount of give between boards ? Someone suggested putting ply under the laminate ? Is it possible to put semi solid or solid on a suspended floor ? I don't want to go overboard as this will be a rental (though done to a good standard).

tenbob1

There has been lots of complaints nationwide in regards to >5mm underlays, it causes too much "bounce", leading to joint damage. If you are set on using it ensure that it has a density of >53Kg/m3 (any decent retailer can advise). Otherwise using the 3mm products will be fine. You can also use plywood to build up your levels, but you also need to use an underlay.

The issue with real wooden flooring in rental properties is that they require a certain amount of care. For the job you are describing a good quality laminate would be recommended.

Mumha

tenbob1 wrote: »

There has been lots of complaints nationwide in regards to >5mm underlays, it causes too much "bounce", leading to joint damage. If you are set on using it ensure that it has a density of >53Kg/m3 (any decent retailer can advise). Otherwise using the 3mm products will be fine. You can also use plywood to build up your levels, but you also need to use an underlay.

The issue with real wooden flooring in rental properties is that they require a certain amount of care. For the job you are describing a good quality laminate would be recommended.

Thanks tenbob1, yes I want to keep the amount of bounce to a minimum. Thanks for the advice re the laminate, I'll definitely go with that.

BoardsMember

I was intending to replace suspended wooden floors with: breathable hardboard insulation between joists (maybe), airtight membrane, ply, then a quality laminate . This is for my own home.

Mumha

BoardsMember wrote: »

I was intending to replace suspended wooden floors with: breathable hardboard insulation between joists (maybe), airtight membrane, ply, then a quality laminate . This is for my own home.

I've spoken to a fair number of people about this, and the general opinion seems to be to not put insulation between joists, but do the airtight membrane sealing to the external walls with a sealant and insulation tape, and insulation tape to internal walls. Also make sure there's an floor vent near the fireplace.

BoardsMember

Mumha wrote: »

BoardsMember wrote: »

I was intending to replace suspended wooden floors with: breathable hardboard insulation between joists (maybe), airtight membrane, ply, then a quality laminate . This is for my own home.

I've spoken to a fair number of people about this, and the general opinion seems to be to not put insulation between joists, but do the airtight membrane sealing to the external walls with a sealant and insulation tape, and insulation tape to internal walls. Also make sure there's an floor vent near the fireplace.

Thanks for the advice. Any suggestions re thickness of ply? Presume would want a floor vent that can be closed?

Mumha

BoardsMember wrote: »

Thanks for the advice. Any suggestions re thickness of ply? Presume would want a floor vent that can be closed?

There are far more knowledgeable people here, who I'm sure will advise, but I'm planning to put a thin ply down, perhaps something like a 9 or 12mm.

Re floor vent, from what I was advised, no, it should never be closed, otherwise you'll end up with rotting floors. When it's near the chimney, it will be dragged up the chimney and out.

Because the house I'm doing up will be a rental, we were advised to make it part of the contract that the renters are expressly not allowed to block any vents.

BoardsMember

Thanks for the follow up response Mumha. If you have suspended floors where the void below has was wall vents, would there be a need for floor grates?

If not putting down insulation, I wonder could keep existing (original) floating floors in place and just put membrane on top of that, then thin layer of ply, underlay and laminate. I know it takes a few CM out of room but for the saving of the labour involved in taking up existing floor it might be worth it.

Mumha

BoardsMember wrote: »

Thanks for the follow up response Mumha. If you have suspended floors where the void below has was wall vents, would there be a need for floor grates?

Again, if there are more experienced people reading this, please correct me if I have it wrong.

My understanding is that with a suspended floor, the air comes in through those vents, and up through the gaps in the floorboards. If you completely seal that floor, the air has no where to go, and you'll end up with rotten floorboards and joists.

If you thinking of wearing a Fleece versus a Windbreaker, the air flows through the fleece. So, putting down the membrane is effectively the windbreaker, however that air underneath needs to go somewhere, and that's why you need the floor vent. If I understood correctly, the chimney will act as a vacuum, sucking up that air from the floor vent.

BoardsMember wrote: »

If not putting down insulation, I wonder could keep existing (original) floating floors in place and just put membrane on top of that, then thin layer of ply, underlay and laminate. I know it takes a few CM out of room but for the saving of the labour involved in taking up existing floor it might be worth it.

That's the direction I plan to go in (with the floor vent !)

BryanF

Mumha wrote: »

I've spoken to a fair number of people about this, and the general opinion seems to be to not put insulation between joists, but do the airtight membrane sealing to the external walls with a sealant and insulation tape, and insulation tape to internal walls. Also make sure there's an floor vent near the fireplace.

Are we talking about first floor 'internal' or ground floor suspended floor 'external'

BryanF

Mumha wrote: »

Again, if there are more experienced people reading this, please correct me if I have it wrong.

My understanding is that with a suspended floor, the air comes in through those vents, and up through the gaps in the floorboards. If you completely seal that floor, the air has no where to go, and you'll end up with rotten floorboards and joists.

If you thinking of wearing a Fleece versus a Windbreaker, the air flows through the fleece. So, putting down the membrane is effectively the windbreaker, however that air underneath needs to go somewhere, and that's why you need the floor vent. If I understood correctly, the chimney will act as a vacuum, sucking up that air from the floor vent.





That's the direction I plan to go in (with the floor vent !)

I don't know where to start, you're so off the mark!

Vents for sun-floor are there to vent the sun floor space

Place breathable membrane/mesh down between or tack under the joists
Insulate between the joists
Air-tight membrane on top of joists taped & sealed
Followed by flooring

Mumha

BryanF wrote: »

Are we talking about first floor 'internal' or ground floor suspended floor 'external'

Ground floor

Mumha

BryanF wrote: »

I don't know where to start, you're so off the mark!

Vents for sun-floor are there to vent the sun floor space

Place breathable membrane/mesh down between or tack under the joists
Insulate between the joists
Air-tight membrane on top of joists taped & sealed
Followed by flooring

Which is why I asked for more experienced people to comment !!!
I've gone back and asked the person who advised me, and in my situation, since I'm installing an electric fire into a closed off fire place, I don't need a floor vent, but I should allow a vent at the base of the chimney.

Also, there isn't much space between the joists and the foundations, in my situation. I could put in insulation there but the Air tight membrane was most important.

BryanF

Mumha wrote: »

Which is why I asked for more experienced people to comment !!!
I've gone back and asked the person who advised me, and in my situation, since I'm installing an electric fire into a closed off fire place, I don't need a floor vent, but I should allow a vent at the base of the chimney.

Also, there isn't much space between the joists and the foundations, in my situation. I could put in insulation there but the Air tight membrane was most important.

Park the fire vent ( you need that but it's a separate thing)
Air-tightness is important but so is insulation

Think of it like this: a light raincoat on cold windy day - wouldn't a woolly jumper underneath be better?