MOre chimney related stuff

[David.WE.Roberts]

Now taking out the hearth (or at least 100mm below floor level so we can put 100mm Celotex in).

We are assuming the hearth goes down to foundation level and is not just a suspended tray.

The fireplace itself (chimney opening) is cleared down to floor level.

Is it worth going down another 100mm to get that extra bit of insulation in?

Looks as though the chimney is single or double brick at the back with no cavity, so possibly that needs insulating as well.

Is there something thin but reasonably effective?

Coming out 4" in a 14" space is going to be an issue, as we are putting various AV/HiFi units in the space.

Cheers

Dave R

[David.WE.Roberts]

Oh, well - every job grows as it goes.

Lounge hearth was a concrete slab over rubble and sand.

The sand looks a bit damp (there were signs of damp in the hearth - reinforcing steels rusted and forcing tiles up) and there is a slight smell of mushrooms which is not welcome except in Far Eastern cookery.

So the whole base is coming out and I am fascinated to see what was holding the sand/rubble in place.

Anyway, I am already below joist level so not too much further to dig.

Cheers

Dave R

[Davey]

You might find an artesian well down there....

[David.WE.Roberts]

:-)

The house is on a concrete raft so that would be a little difficult, unless of course the raft is floating....

The rubble was contained by brick piers and went some way under the floor boards on both sides. I have no idea why because all that does it migrate any damp away from the fireplace and under the floor boards. The concrete slab forming the base of the fireplace and the hearth only covered the central part of the rubble, with two thin boards as shuttering at the sides.

Anyway I can now see that the damp is coming through the outside wall under the DPC where the wall is below ground level. Four brick foundations and outside ground level around two bricks below damp.

Now that bit of wall is open to the air I assume that it will dry out fairly quickly and not need any further treatment as the void under the floor is well ventilated.

[The 'well ventilated' is one reason we are insulating under the floor.]

So the challenge now is to fit an extra joist (or perhaps two) to support the new floor which will now fit right into the old fireplace.

Cheers

Dave R