Replace (suspended) timber floor, or put further timber floor on top?

[Misunderstood_Fox]

Hi all,

Long-time reader of the useful discussions on here.

We are looking to upgrade our suspended timber ground floor which is currently very drafty (due to 4/5 vents) with larger gaps/holes than we would like with a little one on the way.

The property is a 1890s/1900s (no DPC as far as I know) and used to house animals before conversion for habitation. The floor appears traditional and is in mediocre condition (no sign of any red flags e.g. rotting etc.). I doubt it is the original floorboard and it does not appear to be treated with anything so is difficult to clean at present.

I appreciate heat rises (we're looking at options for the roof too) but since deciding to upgrade the floor, thought it worth insulating the floor if possible whilst we're at it.

My initial thoughts are that it's likely to be more expensive and disruptive to replace (we have kitchen units and furniture), though that might make a neater job and mean that underfloor insulation could be installed simultaneously. Afraid I cannot find the link the the thread but the optimum method for the latter seemed to be a semi-permeable membrane on top of the joists and breathable insulation secured between the joists with chicken wire/ SPM securing in place.

Putting a further floor on top of the existing floor could create issues with height of doors/cupboards and also one of the plug-sockets which is very close to the floor. It also appears that the new floor would have to go the other way across the room from the current floorboards. There's also a hatch to the floor below that we would like to keep. That said, it should be possible to put an insulating layer of material down between the two floors that could do the trick with less disruption overall?

Grateful for any thoughts!

 

[Toby Newell]

I restore, conserve and finish period floors for a living. Any insulation can trap moisture. Your easiest cheapest and best bet is fill the gaps to reduce draught. Wood is a very poor conductor (when dry!) but has high emissivity so a reflective insulator can be efficient. Only issue is metal foil is a good condensing surface for moisture.

If you have gale force 9 coming through filling the gaps will give you most of the benefit.

 

[Toby Newell]

Sheeps wool absorbs moisture when exposed to fresh airflow, which reduces insulative effect. Horrible mineral wool is possibly the overal safest bet. Old houses were specifically designed to be leaky. I only fit insulation at the insistence of my clients, under protest, on the ground floor.

 

[fernicarry]

Fixing a breather membrane under the floor is the single best intervention I've made here. Noticeable uptick in comfort levels. Used to be a case of you'd hear a gust of wind outside then a few seconds later you'd feel the air inside move too. No longer the case.

We have big gaps between some boards, enough to see daylight through from below. Could have filled the gaps but then I'd have to refinish the whole area. Easiest approach was the membrane, putting aside the several days of crawling around in the muck on my belly...

Whats wrong with your existing floor that makes you want to cover it up? If its just cosmetic then that can be addressed as can the draftiness.