How to turn damp hearth into a delectable hearth: Part 1

In his dreams!!

Yup, this is how I spent lunchtime, torch shining, baseball cap off and head down a sub-floor. Hard to believe it started with the below image, our client’s idea of hearth perfection…..

So. How come I ended up shovelling five bags of damp earth and rubble? Our client had asked a tiler to create the above and as soon as he lifted some of their slate tiles to replace with reclaimed beauties like the ones above, he found a very damp hearth and ran a mile as he didn’t have a clue how to deal with it. As we were sorting some building work in the client’s bar, she asked if we’d take a look – not knowing I’m the Damp Queen 😉

Mr M took up the tiles and got cracking with the hammer….

We got stuck in. Working out what to do, why to do it and how to make it possible to create a fabulous fireplace from this soggy hearth.

I was worried about the timbers beneath the floorboards, i.e. the joists which hold up the floor. If the hearth was so damp, what was going on below? In properties like this one, a turn of the century 2 bed city mid-terrace, raised ground levels externally often cause ventilation issues, current high water tables through extreme weather conditions, failure of original damp proof course etc – it’s all about What Happens Below.

Yes, our client could’ve just tiled the hearth but sensibly, she wanted to check out the cause of the damp. If you own a house, you need to care for it. If you see a symptom of illness, do a bit of investigation. It’s your householder duty!

As we shovelled out bag after bag, it became clear that the joists to the right of the hearth had previously been replaced, as you can see above. The new ends had been wrapped in protective plastic (though not the preferable dpc membrane). Half a job though, the new ends had been reinserted into damp earth and the original contractors hadn’t bothered to protect the joists to the left of the hearth. We made sure the joist ends to the left and the full length joist to the front of the hearth was exposed and had good air flow around them. The joists to the left hadn’t suffered any substantive decay, so….. the outlook was good and I was pleased for the client – very little work required!

Diagnosis: Leave the hearth opened up for few days to air the joist ends and treat ends with preservative. As there’s already decent sub-floor ventilation, shutter off main hearth section & cement, leaving the front section clear. Use marine board to board the hearth section. Then tile!

Major H&S Risk Assessment: Spiders from sub-floor emerge and scare the bejeez out of arachnophobic client.