Insulation to use under floorboards at outside door?

11
Posted 7th Nov
This door had always been a bit drafty so I redid all the silicone sealant on the outside and adjusted the hinges and the locking bolts to fix the compression at the weekend. So far so good, all the draft from around it is gone.

Now though there's cold air coming up through the floorboards in front of it, it was probably always there and i just assumed it was because of the drafty door. Outside there's a plastic panel at the bottom of the door (marked in red in pic), when i was redoing the silicone I noticed that behind the panel it's just empty space under the floorboards so i'm assuming the cold is getting through the panel into there even though it's sealed tight, maybe because it's just a couple of mm thick upvc.

Any ideas what I should use to somehow insulate behind it?

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11 Comments
Not sure if it's ok to seal up or not but remember that there needs to be airflow for the house this might be vital to that.
Take the panel off and put some kingspan insulation board in there then silicone panel back on. Your house has probably got airbrick around it so it won’t harm the circulation of air in the house
As above, seal the loose edges with a roll of insulation foil tape to help in case of rodents.

Cut it to fit tight! tamp it in with some wood & a rubber mallet.
Scotland131407/11/2019 10:21

Take the panel off and put some kingspan insulation board in there then …Take the panel off and put some kingspan insulation board in there then silicone panel back on. Your house has probably got airbrick around it so it won’t harm the circulation of air in the house



Mr_Gus07/11/2019 18:47

As above, seal the loose edges with a roll of insulation foil tape to help …As above, seal the loose edges with a roll of insulation foil tape to help in case of rodents.Cut it to fit tight! tamp it in with some wood & a rubber mallet.


Thanks guys.

Just to be clear i'd cut a piece to fit in, roughly 1000mmx150mm and wedge it in vertically then seal around the edges with foil tape?

Is there anywhere that sells smaller sheets? Seems to be ~£40 for 2400x1200. The price is fine, it's just the skinflint in me knowing i'd only be cutting a relatively small strip from it.
I'd cut it tight then foil wrap the exposed ends myself, it all go's towards heat reflection & damp resistance.

Then add some tape over the edges where it abutts the wood?

Pack it in all over but leave a gap over the top rather than making the void completely solid #Airflow
for instance if I was putting some in a flat roof i'd need to leave 50 mm air gap, have the kingspan / similar to max depth beneath it & tape the edges to the timber roof supports before sealing it in with a ceiling.
Edited by: "Mr_Gus" 7th Nov
Zooicidal07/11/2019 19:15

Thanks guys.Just to be clear i'd cut a piece to fit in, roughly …Thanks guys.Just to be clear i'd cut a piece to fit in, roughly 1000mmx150mm and wedge it in vertically then seal around the edges with foil tape?Is there anywhere that sells smaller sheets? Seems to be ~£40 for 2400x1200. The price is fine, it's just the skinflint in me knowing i'd only be cutting a relatively small strip from it.


Builders skips & freecycle!
Yip that’s what to do. Have a look at gumtree u should see something on there or if there’s any houses being built near you ask for an off cut
Maybe consider a multi foil insulation, if you live in Stoke on Trent i can give you a small peice for free same issue with this it come in abit roll.
Also just thought how much gap is there if it's a small gap expanding foam maybe easier and better too seal it and if it's a really large one maybe better too use normal insulation as that one shouldn't affect issues with breathability
If you leave the 50mm air gap then you are allowing the wood to breathe.

OP hasn't stated whether its old property & wood or modern, might mke a difference as to what they want to do especially if "heritage".

The PIR foil faced foam boards have a semi DP membrane (the silver foil) of course the OP could also put some DPM (one way breather membrane (again another scrap size obtained cheaply) in place too but likely too much faff !?

OP is it an older property onto bare soil (ie cold rising from ground) & making presennce felt as air passes over it or leaky to air breeze?
Mr_Gus09/11/2019 16:04

If you leave the 50mm air gap then you are allowing the wood to breathe.OP …If you leave the 50mm air gap then you are allowing the wood to breathe.OP hasn't stated whether its old property & wood or modern, might mke a difference as to what they want to do especially if "heritage".The PIR foil faced foam boards have a semi DP membrane (the silver foil) of course the OP could also put some DPM (one way breather membrane (again another scrap size obtained cheaply) in place too but likely too much faff !?OP is it an older property onto bare soil (ie cold rising from ground) & making presennce felt as air passes over it or leaky to air breeze?


It's an old miners house (terraces) that's been divided into flats. One flat on the bottom floor and mine on the first, stairs outside up to the front door. Walls are big blocks of sandstone.

The front door is upvc, there's a panel at the bottom of it that's ~1 meter by 15cm and a couple of mm thick. Behind it is a massive space between my floorboards and the downstairs ceiling. If i take it off i can see to the other end of the room.

That side of the house takes all the brunt of the wind off the east coast but i've sealed what i can and it's not draft, i think it's the cold going through that panel and coming up through the floorboards.

I wish i could explain it better
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