Ground floor sub-floor advice

[AndersonC]

I'm confused about what to do with my ground floor.

Within the front 'half' of the house the flooring consists of pine boards nailed into bitumen/asphalt which I assume is on top of concrete (house is about 80-90 years old).

The boards are in a sorry state and as I am renovating the place want to remove them. Within one corner of the living room a few exhibited dry rot at their ends so these few have come out. This revealed that the bitumen is a little uneven/rough especially at the edges of the room.

Removal of the boards is not a real issue, other than the nails in the bitumen which either break or pull a bigger lump of bitumen out with them.

The killer question is - what to put down to replace the boards? I intend to fit solid oak as a final flooring layer so I am only after sub-floor advice.

Do I need to consider:-
Self-levelling compound?
DPC?
Foams/underlays?
Boarding out with plywood?
Thermal aspects - I doubt the floor is insulated?

If necessary I can post a few photos to help, I would really appreciate any advice - cost/scale of work isn't really an issue, I want to do it right.

 

[mattysupra]

i think i would remove the boards and then check for moister problems in subfloor. Depending on what you find underneath, i cant really say any more about floor prep yet. If you could post some pics it would give a better idea of the work needed.

 

[AndersonC]

Thanks Matty.

 

[AndersonC]

I've got some pictures of the current boards and a couple of areas where I've lifted a few.

The small area of rotten board, about 3" into 4 or so boards from the ends was up the corner (behind the bags of plaster!)

More detail showing the bitumen below the boards that had rotted at their ends

I've also chopped a bit out, on the opposite side of the room, to infill a 'trench' where I removed a lead water pipe (classy radio eh?):-

This job resulted in one of the boards into the hall being lifted up to fill more of the trench

The general condition of the boards in the hall is

Hope the pictures provide some idea of the current state. I can pull the boards up, however I am slightly concerned that this might result in damage to the fairly brittle bitumen below due to foot traffic. Any advice would be really appreciated, thanks.

 

[mattysupra]

im not 100% sure but i think the bitumen on the floor is being used as a surface dpm. If it is a surface dpm there are a few things you need to do if fitting solid wood. Your first problem is if it has been damaged (by nails etc) it will no longer be a working dpm. The correct method when you have this problem is to dig floor up and lay new concrete, insulation etc to todys regs. If this is not an option get back to me for other methods of repair. You could also do with getting some one to tell you what kind of floor it is as im guessing here.

 

[AndersonC]

Matty

Thanks again for your help.

I also think that the bitumen is a surface DPM and can only assume that it is laid over a concrete substrate. I don't know the thickness of the bitumen relative to the length of the nails so can't accurately estimate the level of damage caused.

Unfortunately digging this all out isn't really an option. Hence I was considering a (probably big) repair job to at least ensure decent moisture resistance and level it.

In terms of getting someone to tell me what kind of floor this is - do you mean to confirm what it is made of, e.g. is it bitumen on concrete etc? I'll see if I can find out.

Cheers
Anderson