Clearing out Chimney Ash Pit

OP, go back an use the search, and read how masses of similar jobs were fixed.
for a starter you need to know the installation dimensions needed for the burner you've selected - you have to work to dimensions to know where to install your lintel.
in pic 2 the lower bricks are glistening with moisture - is the flue back wall an outside wall?
theres a capped off gas pipe needs isolating as near to the meter as possible - and then removing the redundant branch, dont leave the stub sticking out of the floor. use a GAS SAFE.
the right hand bit of joist is rotten - more floor boards need lifting to examine the condition of the trimming.

Looks like you may have a little more work to do sorting this, but it's all do-able.

Get a couple of the boards lifted, so you can see whats going on, post some pics.

My last floor was similar, wood straight on bricks and a bit rotten etc.
I renewed and made sure the sub floor ventilation was clear... and I added a few more vents... don't think you can over do it!

Keep us posted.

Thanks again, will get the boards lifted and show you more of whats going on. I have also researched previous threads but it's not entirely clear 'exactly where' the source of damp is coming from, more like a combination of solutions like get a new dpm in there, replace joists, add a new airbrick or lower external ground levels.

In the meantime before I lift floorboards, here is the external wall to the end of terrace house we are in. The fireplace in question is roughly where I have marked the X.

There is a gradient to the path (and whole house) and so the 1st airbrick is closer to the path than the 4th airbrick.

We will be hacking all this cement off in July, drying out and rerendering with lime. The bell cast will be sorted out and painted in breathable mineral paint.

If ground levels are in issue, I have about 2 weeks to sort out before scaffold goes up!

I'm sure others will comment, but I'll start.

As there is render right down to ground level, any moisture can be wicked up by the render, breeching the houses DPC (just above air bricks) and continue it's journey transferring moisture into your floor joists/boards.

If it was mine to sort, I'd look at taking the render off, perhaps you only need to do it, a brick above the DPC level.
Also I would make a pebble trap along the length of the house... Cut a trench 8 inches wide from the house, and 6 inches deep, scoop everything out, fill with large-ish pebbles.
It will stop moisture transferring to the wall, and with the render hacked back, will stop it advancing up the wall.

What size is the fireplace room? and are there air vents on both sides? and how many?

Hi Mr Chibs, thanks for taking the time to reply

Agree on the render and it is all coming off next month, I have put in a french drain before on a basement flat and see them recommended alot to sort damp problems. Current thinking is a proper bell cast on the render dripping on to new path flagstones that slope and immediately run water away from the house.

It's a lot of moisture to be wicked up and result in the saturated the floorboards, could the moist air be drawn down through the chimney as well?

The room is a 4.7m x 3.2m front lounge with a total of 3 airbricks (2 on side elevation).

All sounds good, kind of teaching you how to suck eggs, sorry. French drain would be better if it’s very wet.

The important thing is to break the transfer, just thought, it might be interesting to see what the dpc is like, presume it bitumen, perhaps it’s cracked in places?

I don’t think moisture will make it to floor level from chimney (perhaps others will have thoughts), but if there is no ventilation or heat in the chimney then there will be condensation different times of the year, and it will just sit there, doing no good.

I would suggest another air vent in the elevation that only has one currently.
I added a few more into my rooms, suspended wooden floors.

Keep us in the loop

An update on the house/damp as we have hacked off the cement render (painfully slow process) to be re-rendered in lime.

The grey lime mortar is mostly nice and dry above the bell cast but the lower level of bricks and mortar were damp and smelt of damp soil when hacked off. Waiting a few days to see if this drys out in the sun and definately considering either a trench of gravel or a french drain alongside this side elevation now.

We have just ordered cast iron replacement air bricks (supposed better air flow than clay air bricks) and considering another air brick as per your suggestion for front elevation, doing this as the render is off it makes sense to do at the same time.

The bitumen dpc is cracked in several places with clay soil underneath but thats no surprise really as the bitumen is probably 130 years old.

Still high humdity around the chimmney but will be interesting to see if this drops as more cement is hacked off. Keeping posting updates as I hope this journey will be helpful for others and I very much appreciate the replies and advice.

Would people install a covered channel type drain (cast iron effect) or a french drain pipe buried in gravel? Or nothing at all, flagstones right up agains the newly rendered wall (original plan).

have you looked for broken drains and leaking waterpipes as a source of the water?

Yes, finally diverted a disjointed cracked drain/soil that run under a kitchen floor that has helped the problem in adjacent dining room massively. Guttering all ok.

Took 6 months to sort out the drain but utilities company did it for free in the end which save a couple of grand. Whilst this dining room does not fill up with water after (baths and heavy rainwater!) there is still damp and a very small pool of clear water under the old Victorian bitumen dpm. Below the old bitumen is clay soil upon which the house sits.

I will try and post some pictures of this area.

Would clay soil take months, years to properly dry out? It seems to get worse after rain or humid conditions, my dream is for a dry oversite/solum but it may be an impossible dream the moment!

Glad you are winning, thanks for the update, I’ve no idea about clay soil drying etc.