Wooden suspending living room floor - insulating and levelling

[RoseAcre1850]

Hi all, my first post. We recently bought a Victorian 5 bed detached property in Suffolk. It has had some extension in the past, but has been very much unloved for the past 15 years. Its habitable, but as we have found out with the recent cold snap, it does not hold any warmth in all rooms. Upstairs is fine, the rear garden room in the extension is fine, but office/games room are cold due to single pane glass, but this is fine. We are looking at that. The biggest problem is the main living room. We have a large 8 pane bay window, all leaded single pane glass which holds no warmth in, combined with an un-insulated suspended timber floor and a large fireplace. Fireplace is great when on, but as an open fire doesnt provide as much heat as a wood burning stove. Yesterday with radiator on full and a fire going, living room reached 16 degrees only...

We have the windows being replaced in the living room as the lead work has warped and the windows would cost too much to do anything with, so going with a heritage double glazing supplier to change it out completely. But i think the bigger problem is the floor. Its approx 7m x 4.8m room, sub floor has some issues as it dips down dramatically in some corners/edges etc, more than possible with just wonky boards. Currently its literally boards on a frame, no ply or anything else below the top boards, so its very cold. I want to pull everything up and re-do it, level it, insulate and then put down a new, flat floor. Im not carpenter, but i am very competent at most DIY, is this something to attempt or should i look to get someone in to do it? Excluding the cost of the final flooring, what would you expect to pay to have the whole sub floor rebuilt and insulated?

 

[Cubist]

It's worth your while considering some of the Secondary Glazing systems for those rooms with single glazed windows. Most such are very simple to install - a drill/driver is usually all that is needed - and just as simple to dismount on the summer should you choose to do so.

Regarding your lounge floor; the dips observed in the corners and at the edges, is there any vertical movement when weight is applied/released? Also, are the central areas reasonably flat AND free of any vertical movement or are there noticeable dips but no obvious vertical movement?

Dips and vertical movement at the corners or on some sides of a floor is usually associated with rot/decay of the joist ends where these usually sit in a pocket in the walls masonry or directly over a supporting timber wall plate or sleeper wall. This is a relatively straight forward problem to fix

Dips and vertical movement of the floor away from any corners or edges of the room is typically associated with aging or decay of one or more floor joists and this too can be easily addressed.

If the floor undulates or slopes significantly in one or more directions this can be more difficult to address depending on the preferred option between level what you have and save the floor or gut the floor and the joists to then replace them all. Both of these options may require additional surgery around door opening, skirting and fireplaces.

You do not have a sub-floor per-se. The void beneath your present floorboards is likely directly over earth or perhaps some kind of hardcore base (maybe). There is likely to be two or three sleeper walls that support the joist network.

Assuming a gut and replace strategy and throwing in a suitable insulation package to can expect costs, for a good quality hardwood floor, to start at around £6-7k for materials plus up to one to two weeks of labour from a two many team so overall ballpark in the order of £10-12k. There are likely also to be incidental costs associated with CH plumbing and electrics for example.

N.B. If a sub-floor consisting, say, of sheet plywood or particle boards were to be required then beside the extra materials costs you would also have to consider the impacts and adjustments required as a consequence of raising the height of this floor. Doors, their frames, skirtings, fireplace surrounds et al may need modification and hence re-decoration and there may be difficulties/issues where the new floor meets another, say in a hallway.

 

[montyjohn]

In your position, first thing I did was do a whole house heat loss calculation.
You can pay for one, but I wanted to do my own so I can play with upgrades and "model" the impact.
It's really useful knowing where to spend the money.

It taught me that upgrading to double glazing has a negligible impact on heatloss, but controlling draughts has a huge impact.
If the windows feel cold, it's probably because they are leaking.

As a really quick fix to draughts through the floor, why is air being drawn up.
As a temporary measure I placed a piece of cardboard across all chimneys. It still leaks a bit, but this is a good thing.

I now don't need to light fires and the house is warmer for it.

I have big bags in my floordoards in the living room, which meant we were freezing with the fire lit.
Now we let the radiator do the work, and without the air drawing through, the room gets quite warm.

Subject to listed building consent, my next steps in the living room will be to lift the boards, place down a breathable geotextile type material, secured with battens, and place sheepswool or rockwool between all the joists. Then relay the boards. This will limit air movement and provide insulation.

I also have a springy edge where hopefully I can just sister the joists into new wall pockets. Below is a basement with a lime plastered ceiling that I really don't want to replace, hence the sistering option.