25 Jan 2019
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United Kingdom
I've dug out a hearth and would like some advice on installing some joists. Please see photos.

As you can see the hearth has left a gap.

The front wall of the hearth supports the cross joist.

I propose the following

1. Keep the cross joist and leave all existing joists as they are
2. Add three short joists from the front wall of the hearth to the gable end of the house. All three short joists will sit on the front wall of the hearth. The other end of two of these joists will sit on the side columns of the hearth. The final joist will sit on a new sleeper wall built on the oversite.
3. Ill put the joists on battens and on a dpc.

See photos.

Does this sound ok, any other ideas

I have a problem with the cross joist which sits on the front hearth wall. This cross joists rests in some mortar on the wall. Should i remove the mortar, put a dpc under the cross joists and mortar it up again.

Advice please

Hearth 1.jpg Hearth 2.jpg Hearth.jpg Hearth_Page_1.jpg Hearth_Page_2.jpg
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I'd put a trimmer across the back where the fire was, and fit the joists to these. This will be more rigid than three independent joists.

Remove any mortar, insert DPC and pack the joists up as necessary.

Knock two 9" holes into the side walls to ventilate that pit.
Hi Woody

Thanks for your advice

So it would look something like this. Thanks that would make it a lot more rigid

Hearth 3.jpg
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as above, with the addition of no need for any new masonry support below the joists.
any bricks in the side fender walls that touch the timber can be knocked out of the way.
slip a length of DPC under the front trimmer where it rests on the front fender wall.
the long trimming joists both run into pockets in the brickwork - check that the joist tails have not rotted in their pockets.
while you are at it you could also check the other exposed joist tails further along the wall?

just saying fwiw but why not open up the blocked off fireplace opening in the chimney breast?
you could then check the conditions inside the opening, any damp for instance.
and sweep the flue.
and re-position your elec outlets.
Hi bobasd

Thanks for your reply

The chimney breast has been removed up to the first floor. Just the hearths left on the ground floor.

We have some rotten joists which need replacing

Yes I intend to put a dpc between the existing joist trimmer and the front fender wall. Currently there is a gap of about 5 mm between joist trimmer and fender wall which is currently filled with mortar.

I will put a dpc and very thin wall plate (made of wood) between existing joist trimmer and the front fender wall
oh OK, that accounts, of course, for the 12" squares of brick - the remains of the chimney breast.
thanks for putting me in the picture.
Hi there, did you finish the project? I've dug out part of my hearth. It was full of clay. What was at the bottom of your hearth? Concrete? As mine was bottomless i think. Looking to get some understanding about what other people experienced. Thanks. I've got a post on what's going on with my case. Still ongoing...

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