Insulating under wooden floor

[noodleaddict]

Looking for some advice. We currently lose loads of heat through our living room (ground) floor. It's a Victorian house with an engineered wood floor overlaying the original floorboards. We're looking at getting the room redone and have two options - 1) remove floor and replace with another engineered floor with a thin insulating layer underneath (whole floor definitely needs replacing for other reasons) 2) remove floor, lift floorboards and install insulation underneath, keep original floorboards and close or seal between the gaps (will depend on condition of original floorboards but I think overall look would be nicer). I'm guessing option 2 will be more expensive but which will give better insulation? Has anyone done either of these? TIA

We did option 2.
Can’t comment on cost as we did it ourselves. Also if you’re paying someone they may do a fancier option!
We put cellitex insulation under the floorboards (between the joists). Very easy to handle - you just cut to size. Then when you replace the floorboards you push all boards hard together using a clamp type device (I’ve forgotten it’s proper name!). Then run thin strips of floorboard to cover any gaps left by the floorboards being shimmied up. Works best on square rooms that are spanning one room only as otherwise you hit bits where it’s hard to squash them together.

It was definitely a lot less draughty after doing that. But I think it would be warmer overall with underlay and a wooden floor. Personally I like the old board look though.

Just to add I’d assume option 2 would be cheaper than 1 as you’re using what’s already there rather than buying a new floor

Thanks, it's a big through room so that could make pushing boards up more difficult. I thought option 2 might be more pricey due to having to lift the floorboards, sand and varnish them, draught proof, extra boards etc but you're right there is the cost of the engineered floor (esp for such a big room). Also I think the insulation layer underneath the engineered floor in option 1 would be quite thin so not sure how much it would insulate? I do prefer the look of original floorboards so leaning towards option 2!

Previously, I had a carpeted floor in my living room. It was freezing. We have a large void under the house, and air would come up from it and chill everything down. We bought a high quality underlay after doing some research on the most insulating types. This, and a well-fitted, new engineered floor, have made the most enormous difference and it's lovely and warm now. I think you would probably get more insulation from properly putting stuff under the floor, but that is a much more expensive option.

Just to clarify: we found there was a huge difference between the best and worst underlay on the market in terms of insulating properties.

We bought our 1930's semi 25+ yrs ago and did lots of insulation . We lifted the old floorboards on the ground floor (some of them had to be replaced with new boards). In the void we attached 'battens' to the length of the existing joists on which we laid hardboard(I think it was hb), on which we laid thick layer of 'fibreglass/wool' (nowadays we would use Ecotherm or Celotex but more expensive) then we replaced the floorboards. The old boards still look good and although the new ones have 'shrunk' so there are some gaps, we still don't have any draughts whatsoever. the mismatch in colour between the old boards and new just does not matter. My thoughts on your problem. If you already have engineered boards then why would you not want to keep them. Discard the old boards in order to get a deeper layer of insulation. Whilst doing all of this as you have a Victorian house you might want to take advantage of the situation and perhaps move a radiator or two to better positions and hide the pipework?? Re kitchen floor, don't be hasty re having timber flooring there. The amount of kitchen debris on a floor is enormous and the constant cleaning of timber in front of the sinks/cooker/food prep area would be labour intensive. Good luck with whatever you decide to do.

Thank you, DP is now leaning towards engineered floor as he thinks even with insulation under the floorboards it will be too cold if we stick with original wood floor only. So hard to know! What we really don't want is to end up with a colder room than what we have now.

A 100mm layer of insulating quilt will give fifty times better insulation than a layer of wood.

How do you know "We currently lose loads of heat through our living room (ground) floor?"

Heat loss from a wooden floor is usually due to cold draughts through the gaps and especially round the edges of the room under the skirting. Which is very easily fixed by stuffing mineral wool into the gaps. It's easier if you take off the skirting or if you have access from underneath. Taking up the floorboards is much more work but enable you to do a better job.

Thanks PigletJohn. Would we get better insulation from the 100mm quilt than we could from an underlay? Or maybe we should play it safe and do both?

I'm making an assumption about heat loss through the floor, mostly because it's the coldest room in the house and the floor is noticeably cool to walk on. No floorboard gaps for draughts to come through but there are gaps under the skirting which are probably contributing.

I guess the fear with option 2 is that we'll still get draughts and so the room won't end up being any warmer. Hence why putting an engineered floor over the whole lot seems appealing.

"Would we get better insulation from the 100mm quilt than we could from an underlay?"

yes, much much better.

I have had a floor with original floorboards and no insulation underneath and the room was always cold, my current house I had the boards taken up, 100mm celotex put between the joists as a pp said and it all taped over etc so no gaps for draughts and the original floorboards put back and it is so much better, I haven't had time one year later to fill the odd gap between the boards yet but don't notice any draughts as the celotex does a great job.

Personally I would go with original floorboards because the look is so much better IMO.

heat rises, so you don't lose much heat through the floor unless there are lots of draughts, which are cheap to fix.
A badly insulated floor brought up to standard won't save much on your heating bill, but since heat rises, you will have a pool of cold air at floor level. Insulating will bring the temperature of that air up and improve the comfort a lot.

Thanks everyone, that's all very useful! We're getting quotes for both options...

PigletJohn - can I please derail slightly and ask you about air bricks?
We have a 1930s bay window house. Single skin bay and north facing. The draught from the airbricks is so bad! Can we put mineral wool in that gap?

no.

Where are these airbricks?

Under the floor?

Or high up in the kitchen or a room with a fireplace?

We have insulated under our wooden floor boards in our Victorian house and omg the difference! My husband did it himself but I don't think it's a more than one day job. We then had insulation and engineered boards put down over the top. So much warmer. Our original boards were totally beyond saving. We also just did the same in our dining room, but left the original boards. It's still a good 4 degrees warmer than it was.

Piglet John, I completely missed your answer sorry.
They are on the outside wall of the house, and about skirting board height, or a tiny bit lower