Insulating suspended timber floor

[LeserattePD]

So we have a 1990s Wimpey’s best house with a suspended timber floor but screed on top as far as we know. We’re looking to add insulation under the floor but have a tight budget. I was wondering if anyone has any experience with or opinions on https://q-bot.co ? 

Would this be cheaper than digging up the screed, adding insulation and then relaying the screed?

 

Other suggestions on how to insulate the floor in a cost effective way would be very welcome too!

[Mike]

7 hours ago, LeserattePD said:

So we have a 1990s Wimpey’s best house with a suspended timber floor but screed on top

If you have a screed on top, it's likely that that you have a beam and block floor. AFAIK, there isn't an approved method for insulating below them, not least because ventilation below is required to remove the risk of long-term rusting of the reinforcement. For any insulation you'd also need to be sure that you were in an area that was Radon-free and flood-free, then work out how to get the insulation tight against the underside of the floor throughout.

 

7 hours ago, LeserattePD said:

digging up the screed, adding insulation and then relaying the screed

would likely be your best option.

[LeserattePD]

15 hours ago, Mike said:

If you have a screed on top, it's likely that that you have a beam and block floor. AFAIK, there isn't an approved method for insulating below them, not least because ventilation below is required to remove the risk of long-term rusting of the reinforcement. For any insulation you'd also need to be sure that you were in an area that was Radon-free and flood-free, then work out how to get the insulation tight against the underside of the floor throughout.

 

would likely be your best option.

😞 low risk Radon area and flooding highly unlikely (we’re on a slight slope, so water is only a problem for the downhill gardens). Though we are on London clay. I guess we’ll have to bite the bullet then or cut that out of the budget completely and just look at draft insulation on that floor. Unfortunately, quotes for what we want to have done have been way over our budget, compromises will have to be made.

[JohnMo]

On 21/07/2025 at 07:14, LeserattePD said:

anyone has any experience with or opinions on https://q-bot.co

No experience but some questions 

 

What is driving the change in insulation?

 

Can you not do carpets and add better underlay? Have you insulated to death every other area, sorted drafts and add suitable ventilation?

 

Why not something like this and wooden carpets

https://www.carpet-underlay-shop.co.uk/collections/thermal-insulation-underlay/products/56oz-heat-insulation-wool-carpet-underlay

 

If hard floor some insulation board and tiles on top 

[Conor]

On 21/07/2025 at 07:14, LeserattePD said:

So we have a 1990s Wimpey’s best house with a suspended timber floor but screed on top as far as we know. We’re looking to add insulation under the floor but have a tight budget. I was wondering if anyone has any experience with or opinions on https://q-bot.co ? 

Would this be cheaper than digging up the screed, adding insulation and then relaying the screed?

 

Other suggestions on how to insulate the floor in a cost effective way would be very welcome too!

 

What's your overall insulation strategy and budget? Insulating a floor is rarely the the most cost effective option. Loft? Walls? Windows? Need to look at the building as a whole.

[LeserattePD]

2 hours ago, JohnMo said:

 

What is driving the change in insulation?

 

Can you not do carpets and add better underlay? Have you insulated to death every other area, sorted drafts and add suitable ventilation?

 

Why not something like this and wooden carpets

https://www.carpet-underlay-shop.co.uk/collections/thermal-insulation-underlay/products/56oz-heat-insulation-wool-carpet-underlay

 

If hard floor some insulation board and tiles on top 

At the moment the floor is absolutely freezing in winter. We’re planning an extension&refurb but the budget is limiting. So far quotes have been far more than what we were told to expect by the architects. Yes, we wanted a lot more insulation on that floor but digging up and redoing it is a chunk of money. We would like hard flooring not carpet (preteen kid and cat, plus partly corridor and an office); also ceiling height is only 2.3m so we have to be mindful to stay within the minimum room height. A couple of cm is doable, but anything more than 10 cm extra isn’t. But yes, ultra slim insulation is my next research topic.

 

Other areas will get better insulation - the windows are very badly fitted atm and cheapest uPVC so those are definitely getting replaced. We’re supposed to have cavity wall insulation but probably very badly done, so that’s another thing that needs to be fixed.

[LeserattePD]

2 hours ago, Conor said:

 

What's your overall insulation strategy and budget? Insulating a floor is rarely the the most cost effective option. Loft? Walls? Windows? Need to look at the building as a whole.

Yeah that is all in the plan too, but the floor redo of insulation is the thing we have identified as a “would love to have but can’t afford to”, so I was looking for cheaper/alternatives to digging it up and redoing it.

[JohnMo]

5 hours ago, LeserattePD said:

ultra slim insulation is my next research topic.

Beware of lots rubbish spoken about great thin insulation it doesn't exist. If it got a reflective surface it needs space to work - i.e. big air spaces.

 

Insulation like I linked to (or similar) could be used under wooden flooring. Thicker the insulation the better it works - but 12 to 25mm will make a world of difference.

 

This in 12mm would possibly need to be bonded to the floor, so it doesn't lift or bow.

https://insulationstoreonline.co.uk/product/12mm-celotex-tb4012-thermal-pir-insulation-board