Is it really worth insulating under ground floor (1900s terrace)?

[Scam]

We’re getting to the pointy end of our renovations where we’re looking where we can save a little bit.

Kitchen is having a couple of walls knocked down to open it up, and then new kitchen installed. As part of this piece of work we’d asked about replacing the floor and insulating underneath. However having chatted about LVT flooring and the cost, the idea of splurging probably £7-8k across the ground floor seems a little unnecessary. The flooring here is actually not that bad to look at. It’s a laminate wood topper/effect but it’s actually ok. What we don’t know is if there’s any insulation underneath. We’re assuming not given the poor state of the rest of the house when we bought it (some original sash windows, roof not insulated at all etc.)

So, suspended timber floor with vinyl/laminate/whatever you call it. Would we really see a huge benefit by ripping it up and insulating underneath?

As mentioned, we have already converted the loft so have the floor and roof there nicely insulated. The back side return roof has been done in the kitchen and they will insulate those rear walls. We will redo the front bay roof in the lounge, and get a new front door (also trash), and most rads are getting replaced too. I’d like to think we’d see a heck of an improvement without bothering with the ground floor?

 

[Rob_B]

I don't know what actual difference you'd see but I wish I'd done it when I had the opportunity. Some netting, a few rolls of insulation and you could do it yourself on the cheap as long as you can get under the floor.

 

[LuckyBenski]

I mean the first question to ask is, do those rooms get cold in winter and does the floor seem cold?

 

[Scam]

I don't know what actual difference you'd see but I wish I'd done it when I had the opportunity. Some netting, a few rolls of insulation and you could do it yourself on the cheap as long as you can get under the floor.

Well the first part is really what I'm asking Unfortunately I don't think we could easily get under the floor but I don't know how we would find out. I don't think there's much e.g. crawl space or anything like that. Possibly just mud, joists, then floorboards and laminate.

I mean the first question to ask is, do those rooms get cold in winter and does the floor seem cold?

We've only been here one winter and it was cold. Especially in the kitchen where we could store beer in 10c in the rear cupboards even when the heating had been on!* We'd have a blanket over us in the lounge but I think my girlfriend would have that regardless.. There was a big draft down the chimney which hopefully we wouldn't have.

But the floors weren't particularly cold being that we wear slippers and it's some sort of wood topped laminate. It's so hard to judge this when it's 27c

But like I say, we've now done/will do the following anyway;

• Loft conversion w/ entirely new roof tiles, membrane + insulation
• Loft floor insulated
• First floor ceilings reboarded, plastered
• Kitchen sloped roof insulated, retiled
• New kitchen windows and french door
• Rear kitchen side-return will be properly insulated (currently single brick)
• Front bay roof in lounge will be retiled, insulated
• Chimney cowels and pots replaced
• Fireplace in lounge replaced, blocked up
• Will be new radiators pretty much throughout

*The kitchen will see the biggest improvement what-with insulating the rear walls and new doors/windows.

I'd like to think we'd see a heck of a difference with all that changing.. but if we get to the end of all this work and get to winter and it's still cold that would be mighty annoying.

 

[lucias666]

Yep insulation in the floor is a definite if you are doing any work to a renovation...

 

[dlockers]

Interested in this too as I'll be lifting the floors in my 1930s house with floating floor. What do you do about airflow?

 

[lucias666]

you insulate between the floor joists leaving the void under them.



More than 10 percent of an average home's heat is lost through the floor. This percentage can be much higher in older homes with hardwood floors—or floors made of other materials that conduct heat and cold

Its a judgement call i suppose... Depends if you are doing it yourselves or paying someone?

I have lived in houses with and without insulation under the floors and for me it is always worth it but i am a builder so its cheaper...

 

[200sols]

Interested in this too as I'll be lifting the floors in my 1930s house with floating floor. What do you do about airflow?

If you are lifting the floor anyway then do it, nothing to lose and a small gain. But it's not worth ripping up a good floor to do it.

 

[SoliD]

Think as above if you've got the floor up it's a no brainer.

 

[~Divine~Wind~]

Yep insulation in the floor is a definite if you are doing any work to a renovation...

We did

Dead easy we just used that 12cm thick polystyrene slabbbig, jablite?
I did lag the plastic pipes as well haha

AS weve no proof tho it doenst show on EPC
Cant go pullign the floor up as we replaced the floorbaords with oak flooring lol

 

[Scam]

If you are lifting the floor anyway then do it, nothing to lose and a small gain. But it's not worth ripping up a good floor to do it.

Think as above if you've got the floor up it's a no brainer.

Yeah, thing is we’re not ripping it up. We’re just removing a couple of internals walls in between the kitchen/dining room. Assumed we would have budget for a new floor and insulation but actually seen as it’s the same flooring through the kitchen, dining room, hallways and lounge then it’s going to cost circa £8-10k to do the lot; insulate and put in new parquet style LVT.

Will speak to the builder this week so find out if they can make good the existing flooring where the walls are coming out. Fortunately it’s the same flooring in the bathroom upstairs (which is being ripped out) so hoping they can take some of that to use. Don’t want it to look like a bodge though! Thing is, the flooring really is ok. It’s almost exactly what we’d choose so it seems rather silly to rip it up just for the insulation… hmm.

We did have a friend from up the road over, he’s self building his extension and although he insulated the new floor under the extension, he hasn’t bothered anywhere else in the ground floor.

 

[dirtychinchilla]

We did

Dead easy we just used that 12cm thick polystyrene slabbbig, jablite?
I did lag the plastic pipes as well haha

AS weve no proof tho it doenst show on EPC
Cant go pullign the floor up as we replaced the floorbaords with oak flooring lol

EPRCs aren't worth the paper they're written on. Utterly meaningless. What we should have is energy intensity measured in kWh/m2. That would actually mean something!

 

[a1ex2001]

Yeah, thing is we’re not ripping it up. We’re just removing a couple of internals walls in between the kitchen/dining room. Assumed we would have budget for a new floor and insulation but actually seen as it’s the same flooring through the kitchen, dining room, hallways and lounge then it’s going to cost circa £8-10k to do the lot; insulate and put in new parquet style LVT.

Will speak to the builder this week so find out if they can make good the existing flooring where the walls are coming out. Fortunately it’s the same flooring in the bathroom upstairs (which is being ripped out) so hoping they can take some of that to use. Don’t want it to look like a bodge though! Thing is, the flooring really is ok. It’s almost exactly what we’d choose so it seems rather silly to rip it up just for the insulation… hmm.

We did have a friend from up the road over, he’s self building his extension and although he insulated the new floor under the extension, he hasn’t bothered anywhere else in the ground floor.

If you are knocking walls down you will need new flooring regardless as there will be a gap where the wall used to be! My advice would be to insulate anything you can now as insulating things seems to almost always involve mess and destruction so when you’ve finished you interior you never ever add it! Suspended wooden floors if correctly ventilated underneath are always cold especially if you are going for a hard finish not carpet and given the current prices of energy it is a no brainier for me!

 

[SoliD]

Thing is it's not just about how much money you bleed out, it's about how comfortable the house is through the year and thus improved living quality which you can't put a value on.

 

[b0rn2sk8]

Generally you don’t need to take the entire floor up to fit it. There is a good video that the Gosforth Handyman posted recently showing how it can be done with celtotex via access holes.

If the void space is big enough to actually get under then it’s really quite easy.

 

[Scam]

If you are knocking walls down you will need new flooring regardless as there will be a gap where the wall used to be!

Haha, yes I'm aware of that Need to talk to the builder about it, to see if he can make good those areas. He is taking the same flooring out of the bathroom so we will have some going spare. If not, we can talk to the flooring company as they may have fitted what we currently have (for the previous owners).

Thing is it's not just about how much money you bleed out, it's about how comfortable the house is through the year and thus improved living quality which you can't put a value on.

Totally agree and this was our mindset initially. But, budget is budget and I'm not convinced we will see much benefit in comparison to all the other improvements we are making. When it comes to insulation we are doing as much as we possibly can e.g. paying extra to insulate the eaves.

 

[dirtychinchilla]

What you're really talking about is preventing heat you generate leaving your house via the floor. Seems like a no-brainer to me, prevent it! I personally think it would be a shame for you to insulate the **** out of everything, and the just leave a hole in the bottom of the house.

Edit: sort of side comment, but in most European languages (which is all I'm aware of), their word for insulation actually translates as isolation i.e., isolating the inside of your house from the outside. If you look at a Passivhaus, for example, the basic principle is that the inside should be isolated from the outside. So they don't just insulate, but they make the buildings super air tight and eliminate thermal bridging, the goal being that no energy from inside leaves the building.

 

[~Divine~Wind~]

EPRCs aren't worth the paper they're written on. Utterly meaningless. What we should have is energy intensity measured in kWh/m2. That would actually mean something!

They do to some of the mortgage companies when they offer "green mortgages" not a lot in it but it all helps haha.

 

[dirtychinchilla]

They do to some of the mortgage companies when they offer "green mortgages" not a lot in it but it all helps haha.

Fair enough. Energy-wise, they're meaningless

 

[dlockers]

you insulate between the floor joists leaving the void under them.



More than 10 percent of an average home's heat is lost through the floor. This percentage can be much higher in older homes with hardwood floors—or floors made of other materials that conduct heat and cold

Its a judgement call i suppose... Depends if you are doing it yourselves or paying someone?

I have lived in houses with and without insulation under the floors and for me it is always worth it but i am a builder so its cheaper...

What is this blue stuff? Is it really this easy?