Any engineers around?

Had a gas stove installed in a kitchen this week replacing a solid fuel one. Below exchange of emails with installers. Anybody any view on whether damage could have been caused by them , as I am certain the crack was not there before they arrived? Thanks.



Cast Iron is brittle and can crack on heavy impacts but it would need to be a direct impact. If the two are related, given they were not working directly at this fireplace, it’s far more likely that the crack was there already and opened up a little with the vibration.

Many thanks BuMble!

I’m inclined to agree. I can’t really see any scenario where the works would have caused the problem. Either way (and more importantly), I can’t see any way to prove it. Probably best to take it on the chin unfortunately.

Thanks Coles2, I think that’s what I’ll do. So thread finished. Cheers

An old crack (that is, the cross section of the material that used to be joined together before cracking) would have signs of age about it - given a fireplace with dirt and zeebo and corrosion possibilities. If the cracked surfaces have a dull, even grey sheen and are grainy in texture then it’s a fresh crack (cast iron is brittle and cracks like glass, leaving a sand-like, uncontaminated texture in the cross section).

You might not be able to see the crack surface itself, just a line running up the fireplace in the case where there’s been no relative movement between the material on both sides of the crack

I’d imagine it improbable that you’d get a crack with works like this stove install. As has been said, cast iron, though brittle, would take some direct force or serious movement in what it’s attached to, to crack. Indirect works - even nominally connected - at a distance are unlikely to affect it.


B.Eng (hons) Mech

York, you’re a very decent gentleman!

Sure I’ll try anyway yet again for free advice :open_mouth:

So now it’s a leak on a flattish roof in an extension at back of old kitchen (period house). I’ve no faith in the builder who came around and had a look at it; said something like we’ll need to move all the ‘cappings’ and ‘resit’ them or whatever and see if that solves the problem.

Would I be silly to have somebody with a brain look at it, i.e. an engineer as oppossed to a buildery chap who spends most of the time fiddling with his balls?

Flat Roof Leaks are either a hole in the roof covering, probably torch on Asphalt given the house age, the other being the parapet wall, under the capping you should have a dpc & cavity closer, to stop rain water running down the inside of your cavity wall and causing dampness, mould etc…

If your builder thinks it your capping he might be right, but have the roof covering checked, especially and corners or bend in the material…

Good luck hopefully it won’t be an expensive fix…

If you have no faith in the builder, it’s time to find a new one. Flat roofs tend to leak in this country - more due to lack of maintenance/repair/renewal by owners rather than a complete lack of builder ability. That said, I have seen flat roof failing in under five years which is more ‘warranty’ than ‘repair’.

Architectural technologist/architect/engineer/builder in that order would be my recommendation if you’re worried. You might consider more than just a quick fix if a more major problem is coming in a few years.

What the builder was talking about was taking the top off the parapet wall, probably checking the waterproofing here and putting them back on. This can be a common area for leaks as the waterproofing overlaps here and any failure would compromise the roof. It might not be the problem though.

Thanks for the replies. Roof is not exactly flat, i.e. is an at angle. It’s a newish (10-12 years) extension and has a kind of metal ‘roof’ top. Cheers

I wouldn’t necessarily distrust a builder or suppose he’s no brain - I know some very good ones who’d outshine anything any engineer I know could add to things (including me). A good builder will be able to determine what the problem is without having to try this and that to “see if that resolves the problem”. If the builder can’t identify what’s wrong before the event then do get a new builder.

A photo of the roof from a clear angle would help as well as pointing to where the leak is (perhaps inside shot)

That’s the problem right there.

And how do I know? Because one of the first jobs I did a very long time ago I left out that DPC and it caused a lot of grief. In normal weather conditions there wouldn’t be a problem, but after long persistent wet spells (like we’ve just had) the dampness would appear on the walls just beneath the ceiling.


The cheapest medium term solution is Thompson’s Water Seal. It’s not the best job obviously, but it will work. You might have to do it every few years.

The next option is to cover the cappings with roofing felt. If the cappings aren’t visible that might be an option.

The best job is to take off the cappings, put in a DPC and put the cappings back down again.

Thanks Coles2 and York.

Coles2, it’s more than damp, when it rains heavily, there’s a trickle of water down the wall and of cousre it’s going black there, etc. With that water sealer, is it a case of just whacing it on with a brush myself on the roof top space above where the leak is? Many thanks

If the cappings are saturated and there is no DPC then (in my experience) it will show up as a significant drip or a trickle. It’s surprising how much water can get through when there is no DPC, particularly if there is a hair line crack between the ends of the cappings. Of course it could still be something else like a good old fashioned hole in the roof, but I’d definitely try the Thompson’s Water Seal first, and maybe some Flashband over the capping joints. Sure, this fix is a bit of a bodge, but it should be effective.

Coles2, thanks. Can I just simply whack on the Thompsons seal myself with a brush on the roof top space above where the leak is?

Just paint it on the cappings with a paint brush.

Many thanks!