What went wrong here: barge looks intact

Calahonda52 · 24-01-2025 03:44PM #1

https://www.rte.ie/news/munster/2025/0124/1492635-storm-munster/

muffler · 24-01-2025 05:37PM

Shows why its necessary to strap the walls to the roof. Wasn't done in this case obviously

tabby aspreme · 24-01-2025 06:17PM

Wind got into the attic space somehow and built up pressure, something had to give then.

T-Maxx · 24-01-2025 06:45PM

Combination of high pressure inside and low pressure outside. Also possibly a bad joint between gable and wall.

10-10-20 · 25-01-2025 12:02AM

https://www.boards.ie/discussion/comment/123095859#Comment_123095859

I was going to mention wall-ties too… wonder what the spacing was?

Also, it's a very clean break and the gable wall capping appears to be complete even though it's on the ground, so was it top-loaded weight-wise and did it weaken the wall by virtue of the weight?

standardg60 · 25-01-2025 12:27PM

Wind caught the capping which was proud of the tiles for me. All one piece so came down as one and took the wall attached with it.

Time to check gables with that capping are strapped to the roof I think.

Mellor · 25-01-2025 12:50PM

https://www.boards.ie/discussion/comment/123095615#Comment_123095615

agree. this seems like the issue.

Gable seems to project, but shouldn’t be an issue

T-Maxx · 25-01-2025 04:15PM

The roof structure is not supposed to hold up the gable wall. Looking at the dimensions I'd say a few piers were needed.p

muffler · 25-01-2025 04:48PM

https://www.boards.ie/discussion/comment/123098167#Comment_123098167

That's not correct but maybe you just didn't phrase things properly. First of all a roof does not "hold up" any gable wall but it is supposed to support said wall. Secondly if properly designed and constructed then based on what I see in the photo the construction element appears to be woeful.

T-Maxx · 25-01-2025 06:54PM

I don't agree with your first statement. But yeah looking at how those blocks just completely came apart there's some issue with the mortar there for sure.

Penn · 25-01-2025 07:14PM

https://www.boards.ie/discussion/comment/123098864#Comment_123098864

Sorry, but muffler is correct. The roof provides lateral stability to the gable wall, usually with the block work strapped to the first two rafters. This is because there's no buttressing to the top of the wall. So it looks in this case like the internal and external pressures cause the section of the wall above the side walls to push outwards, and without the gable wall straps to tie it back to the roof it split at the weak point and took part of the roof with it.

Can see in the image in the first post that there are no horizontal timbers between the rafters where the straps would normally be nailed. Usually you require a minimum of five straps between the wall and roof. There's clearly none on the exposed side, so likely none on the other either.

To me, that's the clear defect related to the building which caused this. The mortar could be perfectly fine, but without proper stability any well-built wall can break like that with the right force. The wall there clearly broke at the weak point, which is the joint where there's no lateral bracing.

standardg60 · 25-01-2025 07:22PM

https://www.boards.ie/discussion/comment/123098864#Comment_123098864

Would have thought it would be normal for them to separate like that on impact. What's clear given the capping ended furthest out is the whole gable rotated as one down to where it was tied to the other walls. Swung straight out of the purlins.

Capping as it was done left it both top heavy and exposed to lateral force, though a one in a hundred years force tbf.

Penn · 25-01-2025 07:45PM

https://www.boards.ie/discussion/comment/123098928#Comment_123098928

The same thing actually happened at another property as seen on RTE's website;

https://www.rte.ie/news/ireland/2025/0125/1492924-galway-house-collapse-storm/

You can see the same issue I described above where there are no noggings visible between the trusses which would be where the gable straps are attached to the rafters.

standardg60 · 25-01-2025 07:56PM

https://www.boards.ie/discussion/comment/123099033#Comment_123099033

And another with the capping above the tiles?

Penn · 25-01-2025 08:02PM

https://www.boards.ie/discussion/comment/123099060#Comment_123099060

Yeah. Definitely would have added to the pressure acting on the wall, but if properly strapped in both cases it's unlikely the same would have occurred.

MrMusician18 · 25-01-2025 08:09PM

The barge over the tiles is not the issue. Strong winds produce large negative pressures on leeward gables like this. Without ties, the gable portion is effectively freestanding.

In the latter example, every house with a similar gable in that development should be checked for the presence of wall restraints.

10-10-20 · 25-01-2025 08:54PM

The perfect linearity of the fault at the top of the walls in both cases is interesting. I'd have to wonder if the wall was moving slightly for a time until the the mortar fracture resolved from front to rear at the weakest point, allowing the complete gable to fail with a clean break. Ie, indicating that it was the persistent pressure changes over time rather than a significant singular gust event.

https://www.boards.ie/discussion/comment/123099106#Comment_123099106

Agreed. Indications of hairline cracking on the gable portion in the form of horizontal and vertical mortar lines being the indicator.

Doolittle51 · 25-01-2025 08:59PM

And another 2 occurrences.

sydthebeat · 25-01-2025 09:08PM

https://www.boards.ie/discussion/comment/123095615#Comment_123095615

Not surprised the first two examples are tiled roofs. Very possible the tiles weren't pointed at all, causing some of them to be removed and then the attic to act as a balloon. Strapping at the gables would have helped.

standardg60 · 25-01-2025 09:21PM

https://www.boards.ie/discussion/comment/123099250#Comment_123099250

The perfect linearity is simply a case of where the wall ceased to be tied horizontally. What that points to is the mortar was perfectly fine, otherwise it would have broken unevenly.

Where it ceased to be tied was the fulcrum, and the capping being furthest away was the point of maximum turning force.

We have two instances of this now, there's not a chance of tile over gable, like the houses in the background of the pic, would blow out in this way due to pressure differences alone.

Calahonda52 · 26-01-2025 05:10PM

The concrete barges are widespread across the west, the theory is that it protects the edges of the slates in high winds.

Are the straps in the regs?

DOCARCH · 27-01-2025 08:51AM

https://www.boards.ie/discussion/comment/123101487#Comment_123101487

Yes, straps (at 2.0m centres) between gable walls and roof timbers/rafters in Part A Building Regulations.

Calahonda52 · 27-01-2025 08:58AM

https://www.boards.ie/discussion/comment/123103452#Comment_123103452

Thanks as always, (hope all is good with you ) the fixings would want to be decent as well

geographica · 27-01-2025 10:58AM

should a lot of home owners be concerned about this? Or are they very rare incidences of building not being done correctly or was this practice widespread I wonder ?

muffler · 27-01-2025 11:53AM

I wouldn't think it's widespread but equally it isn't rare either. I have seen some terrible strapping details ranging from no straps at all to attempts to fix steel strapping after gable walls and roofs are fully constructed. Similarly I have seen un-stamped structural timber being stamped after the event.

It really is shocking the amount of shoddy works that have been carried out over the years and still going on and will continue in a similar vein until such time as the government implement a proper building control scheme.