Steel exterior banding causing leaks

[Balaphuel]

Hi,
First post on this forum, I must say there's a treasure trove of useful info on here.

We have an old (1877) tenement flat in Glasgow which has steel banding fitted around the whole building. During the wet & windy weather we experienced last week, there was water leaking though the top of every window down one side of the building. One of the bay's was particularly bad, with around 6cm of water collected in a bucket within a 3 hour period. The steel banding is located just above our windows. The factor sent a builder round today who reckoned it was caused by water leaking past the bolts going through the banding & into the stonework. He said it could be fixed by pointing cement into the corner where the steel banding meets the sandstone walls. I have my doubts though as they have been to repair this last year with silicone & also 3 times before that when it was the previous owners.

So my questions are... Would cement pointing be a long-term fix? Surely it would eventually break free from the steel as there is no adhesion, then continue leaking? What would be a proper long-term repair for this problem? I imagine it might involve removing & reinstalling the bolts in a watertight way.

Thanks

 

[worms]

Balaphuel, welcome to the forum!

I'm afraid I can't offer any expertise on this but it sounds like you need it fixed! I would have thought it strange to have so much water coming in, simply by tracking along the bolts. Has the steel belt altered the way water is shed by the front of the building? Presumably you are not the top floor flat and the belt is the only likely reason? The belt is there for a purpose (presumably subsidence from old mine works?) and I presume that the water ingress isn't related to the original problem that caused the belt to be fitted in the first place?

 

[Balaphuel]

Hi,

I agree we need it fixed urgently, I just want to ensure its done properly. I get the impression the factor would happily do a quick fix, which I'm not accepting. I don't think the steel banding has changed the way water is shed by the building. Were on the first floor, the building has 3 levels plus a basement. The problem only occurs when we get a combination of heavy rain & high winds, so it would seem that the wind is driving the water in. There must be a lot of water running down the wall when its raining heavily, more so by the time it reaches the first floor. There's no alterations to the building above us which would change how water is shed either. These steel belts are a common feature in old buildings here, they seem to have been used mainly as a preventative measure. Your right too, there is a history of old mines in the area & this is the reason the banding was fitted originally. I think the steel belt was fitted in the early 90's. The stonework looks in good condition & our neighbours above don't have any leaking, so the problem would appear to be coming from the banding.

Thanks.

 

[chuckey]

If the steel band has been up since the 90s, I would think that the crack between it and the building will have filled up with dirt, so water running down the face of the wall might flow along the top of the strap until it can get out (into your flat?). I think that a waterproof fillet along the top of it, shedding the water would fix some of the problems, because now the holes in the stonework into which the bolts are fixed would be protected. Ideally the bolts should be taken out and a rubber gasket washer should be used under its head, so water cannot run along the bolts.
Of course, I would guess that the stones moved, so causing the need for the strap, were they repointed properly when they were pushed back into line. Are their tops actually flush, or weather pointed, because if a block is sticking out, water could run in on this "ledge".
Frank

 

[Balaphuel]

Hi Frank,

That's an interesting point you raised about dirt being between the strap and the building. I'm sure if this was cleaned out it would help the situation. Though there are 2 different types of strap on the building, there's a small flat strap (looks like a flat steel plate) going around the bay window which looks like it wouldn't have a gap between it & the wall. This is the worst effected area, possibly because its hard against the wall? The other strap type is this shape "[" & it looks like there could be a small 5mm gap between it & the wall.

What material do you think should be used for the waterproof fillet Frank? When the builders came to look at it last year they used silicone to go around the bay window strap, without much success.

Also, who would be the right trade to undertake a bolt upgrade? At the moment the guys who came round are roofers.

Thanks

Ray

 

[middi]

Cement pointing above the steel band would not last " ten minutes".
As soon as the metal expands in warmer weather and then retracts when cool, the cement " seal" will crack.

If it can be correctly ascertained that the water entry is via the banding securing bolts a better, cheaper repair, would be to use modern silicone above the steel band. If this is done correctly, ie:- clean pointing above band and well cleaned stonework and if necessary a " bonding groove" cut just above the band, this would work. It is also extremely important that no sealing whatsoever is done below the steel band.
If " mastic" sealing has previously done ( but not very well !!!) water travelling along the band would accentuate the problem at the entry point. IF the band has also been sealed from below the band, this would act as a " bucket", water will accumulate behind the band and divert it into the bolt holes.

Also if it should prove too expensive to repair/replace the belt/band/bolts, then a lead flushing could be inserted above the band into the stone work, as long as this lead is protected/insulated from direct contact with the steel

Middi

 

[Penners]

Welcome to PPUK, Balaphuel.

I think Frank has raised a possibly pertinent point above. If the banding is, in effect, a "belt" around the whole building, what symptom was apparent that forced the decision to fit it? If it was because of mine workings, I assume the building was moving in some way - a belt suggests that it was pulling apart.

If this is the case, then I wonder whether there has been some differential movement between the area of masonry constrained by the band and the area that isn't. I could imagine the possibility that this would cause some cracking/separation of a mortar layer - perhaps under the band - that might allow water ingress.

Of course, the only way to investigate this would be to remove the band, and I don't know whether the factor would wear this, bearing in mind that it's only a possibility.

As Middi has suggested, a proper flashing job, with lead set into a mortar joint above the band and protecting the band from rainfall, could be a practical solution.

Would you be able to post some pictures of the banding?

 

[Balaphuel]

Hi,
Thanks for the info. I shall take some pictures tomorrow & post them up.

 

[CatherineB]

Crikey! 7 posts before someone asks for pictures? You're slacking, chaps!

(Belaphuel, welcome to the forum - you'll find there's lots of useful info and advice, as you say, as well as a passion for PPUK "porn" (aka house pictures))

 

[worms]

There must be a lot of water running down the wall when its raining heavily, more so by the time it reaches the first floor. There's no alterations to the building above us which would change how water is shed either.

Balaphuel, in common with half the population of the known world, I once had a flat in Partick, so I know the sort of banding that you are talking about.

I'll be interested to see the pics in due course, but one of the features of most Glasgow tenements (as opposed to Edinburgh ones! ) is the level of detailing which helps shed water. Most bay windows have a ledge above them which takes water out and away. It will be interesting to see how your one looks and where the steel band is in relation to the windows and lintels.

 

[Balaphuel]

Hi,
Here's a picture of the side of the flat & the banding above the windows on the 1st floor.
Worms, i'm in the Southside of Glasgow, I know Partick well having previously lived in the West End for years. I agree, we are spoiled for nice old buildings up here.

The area around the building does have a history of old mines, but I don't think subsidence or shifting stonework is the problem here. I have seen no evidence of shifting stonework. The building had a major renovation in the early 90's including a complete new stairwell, many of the internal walls are now plasterboard & sadly all the cornice work has been removed. As a result, the building is generally in good condition for its age. I did an apprenticeship years ago in ornamental plasterwork, so its my intention the reinstate all the cornice using the same techniques that were applied originally, I just need a lot of spare time!

Thanks

 

[chuckey]

From Pic, L.h. lower bay window, just above the "lintel" blocks(below the band), from the centre , about 16" long, there is a piece of material visible which is running to the left, which is not on the other side of the centre line. Is this the original pointing and the rest has fallen out? I think you will need a telescope to see this !!
Frank

 

[Balaphuel]

Well spotted Chuckey.

Here's some pictures of this area. It looks like a missing section that's been filled with either silicone or cement.

 

[CatherineB]

Wow, I don't know what I was expecting, but what a beautiful building!

 

[Penners]

Is that area that Chuckey referred to anywhere near the leak? If so, I reckon he could be on to something. The close-up photo shows some silicone (?) repairs to the mortar line, and on the face of it they don't look very good.

Just above that mortar line is a course of slightly projecting stone. I wonder what the mortar line above it is like. If that were in a similar state, then I reckon it could well be the source of the leak.

 

[chuckey]

That little projecting edge of stone is the drip rail, designed to shed water. While it looks trivial, the original builders thought it was necessary. It is difficult to ascertain if the silicone has made a waterproof seal, or not, but it certainly won't shed any water. FWIW, I have found that silicone will not adhere to natural stone over a period of more then a couple of years,it looks OK but I can lift it it in one rubbery lump. Tried to patch up cracked limestone blocks, else I will have to open up the cracks to say 1/4" and use lime pointing mix. Its a major job for every crack.
Frank

 

[Penners]

I agree, and the little ledge in question would be a prime candidate for causing an accumulation of water on its top edge. If the pointing there has failed, then water ingress could occur.

 

[worms]

Balaphuel, I know the South Side very well and recognise the carved detailing on the stonework, but can't quite place the building...yet!

Like I said above:

one of the features of most Glasgow tenements ... is the level of detailing which helps shed water. Most bay windows have a ledge above them which takes water out and away. It will be interesting to see how your one looks and where the steel band is in relation to the windows and lintels.

I would agree with what the others have said and want to to look at the water-flow and pointing before blaming the bolts.

 

[Balaphuel]

Thank you all for your very helpful comments... & sorry for such a slow reply, I've been away these past few days.

Worms... the building is tucked away in Mount Florida. Do you live in the Southside yourself?

The area that leaks most in the bay window is on the right side of photo at the external corner. Though I'm sure water from the patched section could still find its way to this corner. Interesting comments regards the little edge & the need for good pointing above it. I'd have to be on a scaffold to check its condition though.

As for the rest of the windows which still leak to a lesser extent, could it be that the stonework just needs proper repointing in the area above our windows?

I spoke with the factor who is waiting on a quote from the builders regards doing the repair. She warned me that they reckoned extensive repointing of the whole side of the building is nessesary. I can't see all of the buildings occupants agreeing to this costly repair during these uncertain times. I may even end up fixing the area above our windows myself. I'm sure I could do the pointing & cleaning of the stone/steel banding gap if I got a scaffold erected. Another item for my lengthy DIY list!

 

[FamilyWiggs]

Looking again at your middle picture - the join between the top of your window frame and the stonework doesn't look too healthy. There sme evidence of repointing and what looks like a wee gap. Could water be running down the face of the stonework and tracking under the lintel and through this weak point? Even more possible in driving wind and rain as you had recently?

Robin