Waterproofing a chimney

[Hobden]

We're going to have a liner fitted in our rather large "ignlenook" chimney. The outside bit of the chimney is tall (we have a hipped roof and the chimney is at one end) and exposed to the weather, and built from ordinary facing bricks. The chap who came to quote for fitting the liner said we ought to waterproof the chimney. He suggested Thompson's Waterseal. Is this a sensible thing to do? I'm worrying about whether we'll be left with brickwork that doesn't breathe, but maybe it's more important to keep the rain out?

 

[88v8]

Faugh!

If the bricks are that porous the whole thing should be pulled down. May need repointing, in lime of course.
Go up and have a look.
Waterproofer? Faugh!!!

However...... when the liner is in and the top plate and register plate, the flue will be closed for the first time ever. So if any damp is getting in through decayed pointing for example, eventually it will cause problems as there will be no ventilation to keep the stack dry. At present, there's so much air going up there, it could be damp and you'd never know.

Therefore, it's a good idea to create some ventilation:

At the top of the stack, a couple of feet down, drill four 1" holes though into the flue. Cover the holes with stainless mesh to keep bees and wasps out.



At the bottom, at the back of the register plate, make a slot so there is a gap of about half an inch, a couple of feet long.
This will create a gentle airflow up the stack and keep it dry.

Such an arrangement has dried our stack, which due to bad pointing inside the thatch where it's inaccessible, got so saturated that we were having floods in the fireplace. Since I created the ventilation, not a drop has come down.

Ivor

PS most unwillingly, I forked out $14.99 to go ad-free on Photobucket. Bliss. Wish I could do the same on eBay. And in some restaurants I'd happily pay a few bob to have the 'music' switched off. Good racket, eh, create an annoyance then charge you for removing it. Speed cameras. I'd pay a few bob to have those off as well.

 

[TheRoost]

It sounds like he's offering an extra service that is profitable and easy for him to do, regardless of whether it's a good thing or not. Has he been up there and seen the chimney prior?

Once the scaffolding is up, inspect the pointing and brickwork for spalling, or get a good roofer to inspect it if you can't yourself. Viewed from the eaves, a chimney can look really sound, but up close can turn out to be a mess of crumbling pointing, with a few spalled brick faces ready to come away. Then there's the flaunching that could be cracked or coming loose.

I wouldn't bother with any kind of water proofing treatment, just make sure the construction is sound while you have scaffolding in place.

 

[Flyfisher]

PS most unwillingly, I forked out $14.99 to go ad-free on Photobucket. Bliss. Wish I could do the same on eBay. And in some restaurants I'd happily pay a few bob to have the 'music' switched off. Good racket, eh, create an annoyance then charge you for removing it. Speed cameras. I'd pay a few bob to have those off as well.

I suppose you can ignore speed cameras, though it will cost a bit more than a few bob :wink:

Which reminds me a of quote about London's bus lanes by the late Michael Winner: "They only charge you £60 to use them, and you get no points. Wonderful value!"

 

[Hobden]

It sounds like he's offering an extra service that is profitable and easy for him to do, regardless of whether it's a good thing or not. Has he been up there and seen the chimney prior?

No, this was just after inspecting from ground level with a pair of binoculars.

Once the scaffolding is up

No scaffolding, it'll all be done from a cherry-picker. Not sure they'll let me ride in it - elf-n-safety and all that

I wouldn't bother with any kind of water proofing treatment, just make sure the construction is sound while you have scaffolding in place.

That's what I was leaning towards, but I needed people more knowledgeable than I to say the same. Thanks!

 

[Hobden]

If the bricks are that porous the whole thing should be pulled down. May need repointing, in lime of course. Go up and have a look.

I don't do heights At least not heights I feel I can fall from and attain some high speed before a sudden stop ...

Waterproofer? Faugh!!!

That's a "no" then?

However...... when the liner is in and the top plate and register plate, the flue will be closed for the first time ever. So if any damp is getting in through decayed pointing for example, eventually it will cause problems as there will be no ventilation to keep the stack dry. At present, there's so much air going up there, it could be damp and you'd never know. Therefore, it's a good idea to create some ventilation:

At the top of the stack, a couple of feet down, drill four 1" holes though into the flue. Cover the holes with stainless mesh to keep bees and wasps out. At the bottom, at the back of the register plate, make a slot so there is a gap of about half an inch, a couple of feet long. This will create a gentle airflow up the stack and keep it dry.

Noted, thanks very much, though I'd probably have to get somebody in. Though I'll talk to the chimney man and see if he's up for it ...

 

[88v8]

This stainless mesh is the correct grade. Needs to be a certain size to keep them out, yet allow air flow
http://www.themeshcompany.com/products/-4-Mesh---5.45mm-Aperture---0.9mm-Wire-Diameter---SS304-Grade---Woven-Wire-Mesh--52.html#SID=59

Fix with brass screws. I drilled the holes over a 4" grid and covered with a piece 6x6".

Cherry pickers do not conduce to good workmanship.
Fly in. Bodge. Fly out.
No use for lime work, bedding, pointing, flaunching, which needs attention over several days.

I used to be bad at heights. Cling like grim death to ladders. Then suddenly I was OK. Never understood why. Now, roof, chimney, whatever.
Not a budding Dibnah, mind you.
Guess it was just one of those psychological problems one needs to get over.
Otherwise one is at the mercy of any bodger who happens along and says ' you need a new roof, guvnor'.

Ivor

 

[Hobden]

This stainless mesh is the correct grade. Needs to be a certain size to keep them out, yet allow air flow
http://www.themeshcompany.com/products/-4-Mesh---5.45mm-Aperture---0.9mm-Wire-Diameter---SS304-Grade---Woven-Wire-Mesh--52.html#SID=59

Fix with brass screws. I drilled the holes over a 4" grid and covered with a piece 6x6".

Thanks.

Cherry pickers do not conduce to good workmanship.
Fly in. Bodge. Fly out.

The guy seems to be well thought of locally. And he did hum and ha over whether or not scaffolding would be needed, but finally decided he could get in with his big cherry-picker, but not his small one. As ever, it's hard to know until the job has been done and settled for a while.

I used to be bad at heights. Cling like grim death to ladders. Then suddenly I was OK. Never understood why. Now, roof, chimney, whatever.
Not a budding Dibnah, mind you. Guess it was just one of those psychological problems one needs to get over.
Otherwise one is at the mercy of any bodger who happens along and says ' you need a new roof, guvnor'.

I agree it's always best to be able to do one's own work, but me and heights just don't get on, at least not on a ladder. I'd be OK on scaffolding as both hands are free to do the work, but on a ladder I follow the first rule of rock-climbing - "three hands on the rock at all times".

 

[88v8]

...on a ladder I follow the first rule of rock-climbing - "three hands on the rock at all times".

Haha!
I have an alternative - 'one hand for the ladder and one for the job'.

Oddly, enough, when I spent a couple of weeks on a pro-built two-level scaffold fiddling with the chimney, I felt less safe. Had to concentrate in climbing the two ladders, transferring from ladders to scaffold, the access holes in the scaffold, the possibility of falling through the rails when I was crouching, climbing up a stepladder on top of the scaffold to put up a heavy electric hoist. It was OK, but needed more concentration than just working on a ladder.

However, where I did have a problem with ladders is wooden ladders. Period ladders. First the horrendous weight of a big wooden ladder. I had a rope-op that I last used to paint the gable of my parents' house when we were selling it. Extending the ladder to full height without it falling over, and then the wobble and bounce and sway. It was a high gable, and up there painting, one hand on the wobbling ladder in the wind, swaying.... when one is accustomed to the rigidity of an ally ladder, it's another world.
I left that ladder hanging in their garage ten years ago, wouldn't be surprised if it's still there.

Ivor

 

[Feltwell]

It's how secure you feel for me, the height doesn't matter. I once walked across the beams of a bridge that was in mid-construction, about 60' directly above live traffic on the M62 - but I was wearing a full safety harness, clipped to a wire rope, with a handrail on one side - so no problem. However, my stepladder with a platform 6' up, I hate using that if it's not on a good solid base.

I've bought a scaffold tower now and it's great, but I still try and secure it to the house if I'm going up high - a ratchet strap holding it to the wall provides added confidence, even though I always use outriggers at the base and it's a double width tower. Buy a decent tower such a Youngmans one secondhand in good condition, look after it and you'll always get back what you paid for it if you wanted to sell it on. For more major jobs they are a lot better than a ladder. I'm with Ivor on wooden ladders, best consigned to history. I've got a very long rope-operated fibreglass ladder that I bought for this house - trouble is it's so heavy I can't ever imagine me ever using the thing! I should really sell it on now I've got the tower (no ladder needed for that - it has a inbuilt ladder on one end, you climb up the inside and through trapdoors in the platforms)

When I do use ladders I've got one of these - well worth the money, makes it so much safer using a ladder on a slope. Even on level ground it grips the ground much better than just the ladder itself.

http://www.ladders-999.co.uk/alloy-ladders/big-grip-ladder-safety-stabiliser-and-leveller.html

My father-in-law caused irreparable damage to his wrist falling off the second step of a stepladder, about 18" up! He overbalanced whilst trimming a hedge. Several operations later and he still wasn't right.

I've got to tackle a chimney stack on my house - repointing plus replacing some spalled bricks - it's at the side of the house so I can get to the outside face and probably the sides off my tower, but to get to the other side I'll have to get some scaffolders in. More expense!

 

[LadyArowana]

...on a ladder I follow the first rule of rock-climbing - "three hands on the rock at all times".

However, where I did have a problem with ladders is wooden ladders. Period ladders.

Ivor

I can relate, went up into my neighbour's roof via the built in Edwardian wooden contraption and it squeaked and groaned and I'm not even particularly big. Much worse than an nice modern aluminium step ladder.