Lining a fireplace in an old stone wall to bedrock

[WoodyAlan]

Evening all,

I am in the process of reinstating an old fireplace in order to take a woodburner. The recess of the old fireplace is already concrete lined and exists in an old stone wall, as per cross section diagram. Unfortunately, during the excavations to get to the fireplace, we had to created an opening in the lining, revealing the base of the stone wall and some bedrock (see pics) and I'm wondering whether this will be an issue.

After doing my homework, I figured a dot-dabbed, fire resistant non-gypsum based board would be good for the lining but I'm at a loss as to what to do with the revealed stone, especially when considering damp issues?

An additional minor issue: The base of the existing chimney lining terminates half an arms length above the register plate and is packed with vermiculite. It should be easy enough to attach an adapter to a flexi liner in such confined space, right? If it needs a screw it'll take some contortionist driver work.

Feedback would be much appreciated. Thanks for your time.

Alan

Cross Section for your amusement

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• WoodyAlan
• 23 May 2011
• 1

Fireplace as it stands (n.b. decommissioned gas pipes enter through the centre-bottom, packed in yellow sand, visible)

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• WoodyAlan
• 23 May 2011
• 1

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• WoodyAlan
• 23 May 2011
• 1

Detail of the revealed bedrock

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• WoodyAlan
• 23 May 2011
• 1

 

[Richard C]

After doing my homework, I figured a dot-dabbed, fire resistant non-gypsum based board would be good for the lining

Do some more homework; silica (non gypsum) based boards are what you need but you can’t rely on dot & dab to secure it in a high heat area. Read this little lot & a it will give you some pointers;
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As this comes up so often, I’ve put together this generic post; read the links but not all may apply to you.

You can DIY but you need to understand the Building Regs (which changed in October), submit a Building Notice & pay a fee. Your LABC will inspect &, assuming everything is OK, issue a compliance certificate; the BI may want to witness smoke & spillage tests. No compliance certificate may lead to difficulties when you come to sell your property; if cannot produce a compliance certificate in the event of a problem, your insurance company may invalidate your policy & reject any claim.

Lots of archive threads on this, & other things you have to watch out for, here a few links for you to read:
http://www.stovesonline.co.uk/stove_building_regulations.html
http://www.hetas.co.uk/public/certificates.html
http://www.solidfuel.co.uk/pdfs/buidling_regs_consumer leaflet.pdf
//www.diynot.com/forums/viewtopic.php?t=183614
//www.diynot.com/forums/viewtopic.php?t=211524
//www.diynot.com/forums/viewtopic.php?t=242738
//www.diynot.com/forums/viewtopic.php?t=224751

& some more sobering just in case you think it’s all a load of old tosh:
http://www.solidfuel.co.uk/main_pages/news.htm
http://www.dailymail.co.uk/news/art...wood-burning-stove-leaks-carbon-monoxide.html
http://www.eveningnews24.co.uk/news/warning_over_heaters_after_norfolk_couple_s_death_1_811099

Also get at least 3 quotes from local independent HETAS installers:
http://www.hetas.co.uk/nearest_member

You might be pleasantly surprised & you should ask yourself if you really want all the hassle & risk getting it wrong; climbing onto the roof with an 8M stainless steel snake on your back is not for the feint hearted!
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There are also examples of using boards in the links & a search will show up others.

but I'm at a loss as to what to do with the revealed stone, especially when considering damp issues?

Do you have damp issues?

An additional minor issue: The base of the existing chimney lining terminates half an arms length above the register plate and is packed with vermiculite. It should be easy enough to attach an adapter to a flexi liner in such confined space, right? If it needs a screw it'll take some contortionist driver work.

May or may not be acceptable; what you doing is controlled building work (as you will see from the links) & you should either be getting a HETAS registered installer to advise/install for you or submit a building notice & have LABC inspect/witness test.

In the meantime I’ll have a look at your pics. after me dinner

 

[WoodyAlan]

Excellent stuff, thanks Richard, plenty of extra homework there.

Regards the damp, it's dry and the opposite side of the wall is internal - no damp currently - but, it's an old house and there is damp elsewhere so I was wondering if there were any precautions I should take?

I recognise it's a controlled job, that's why I'm keen to know if what I'm doing is right. Although, yeah, as you say, getting a HETAS engineer in to do it would certainly reduce the hassle.

Enjoy your tea.

 

[joe-90]

Richard. If you were a lawyer you'd charge over a thousand pounds for that in-depth advice. Yet you give it away free?????

 

[jrplastering]

thats because hes an absolute legend joe

 

[Richard C]

Richard. If you were a lawyer you'd charge over a thousand pounds for that in-depth advice. Yet you give it away free?????

Basically I’m just a nice bloke who wants to give others the benefit of knowledge, experience & understanding.

thats because hes an absolute legend joe

Wow I’m both flattered & humbled

I could tell many, many stories but for 99% of folks, it would be totally boring & for a lot of others would just be troll bait & I do tend to attract bit of that lately .

 

[jrplastering]

no worries mate as im sure ive said before ive been in this game for 10 years and will always be learning to the day i retire, but ive learnt an awful lot from ya rich, cheers pal

 

[hotrod]

Do some more homework; silica (non gypsum) based boards are what you need but you can’t rely on dot & dab to secure it in a high heat area.

I've not had chance to go through the links you provided Rich, but a possibility is maybe using the Gyplyner system and Supalux, like wot I did wiv mine.

I won't include any pics Rich - I know you're sick of looking at them .

 

[WoodyAlan]

Nice to see the amount of respect on the board. But, cuddle time's over, fellas

@ hotrod Cheers for the extra suggestion. Gyplyner? sounds like its Gypsum based? but I'll check it out for sure.

I guess my main question, what should i do to fill the dirty gaping hole at the bottom of the recess? I need it ready to render or board up, so, would it be okay to lump some concrete in there? with a heat resistant mix? Or is it okay to board over it as it is?

Basically, this needs to be filled square and true:

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• WoodyAlan
• 23 May 2011
• 1

Thanks again.

 

[Richard C]

Gyplyner? sounds like its Gypsum based?

"Gypliner" is a metal framing system, Hotrod actually used “Supalux” fire protection boards which are calcium silicate based not Gypsum. His project involved constructing a false chimney breast for a hole in the wall gas fire which is somewhat different to yours.

I guess my main question, what should i do to fill the dirty gaping hole at the bottom of the recess? I need it ready to render or board up, so, would it be okay to lump some concrete in there? with a heat resistant mix? Or is it okay to board over it as it is?

I would definitely fill the hole; use a sand/cement/lime render mix & fill it out in at least two stages; info on this in the archive links I posted.

You can board it out but as I said don’t just rely on dot & dab, you need to mechanically fix or it will probably fall down in a very short space of time. You could also consider rendering it after filling the hole but that looks suspiciously like tile cement on there to me so you need to get rid of that before rendering; use a 2 coat sand/cement/lime render with the second mix slightly weaker. Don’t know what sort of fire surround you propose but don’t use Gypsum plaster to dress up the area around the opening either, it will fall off. I would also get existing liner checked out for condition/suitability before doing too much work on the fire opening itself.

The opening doesn’t look very big to me; can you get a freestanding log burner in there? It depends on the “look” you want but have you considered an inset stove? We have a multi-fuel which offers greater flexibility & higher heat output, 8Kw in my case.

 

[WoodyAlan]

Richard, thanks for the information once again.

I've got some lime in store so I'll get the hole filled as you suggest. Beyond that, I might render/board the recess and tile up the base but let a HETAS engineer deal with the rest, depending on my ambition when I come to it. Whatever the case, I thank you for supplying info on mixes and such. And yes, that is tile cement .

As for the opening, the pictures don't do it justice and my diagram is way off scale, the recess is actually plenty big enough (up to standard, too!) and since we already have a decent wood burner (plus a ready supply of wood), that'll be what's going in there.

Cheers