Windpost late addition

Gav T · 3 Jul 2019

Hi. First time poster. We’re taking out an external wall to fit 5.5m bifolds. There’s a 6m rsj to be installed above the bifolds and the piers are to be rebuilt from foundation to beam using 215x440 padstones. This is all fine but our SE has recommended wind posts either side of the bifolds at the 11th hour. (After submitting calcs to building regs). Do we really need windposts? We’ve now paid an architect who believes this is overkill and is coming for a look on Saturday to give his view in person. This architect has been recommended by the builder whose also frustrated at this last minute, expensive addition (the windposts) please help with your views as i want this to be long term safe and correct. Thanks

^woody^ · 4 Jul 2019

Is the architect qualified in structural engineering to be able to make that assertion? Will his insurance cover him for structural design?

Is the builder recommending a person who will just back up the his own unqualified opinion?

Gav T · 4 Jul 2019

I will call the architect today and find out as it’s going to cost me £250 after his visit. I’m thinking I just bite the bullet on the extra £750 for the windposts but why didn’t the SE recommend these first time round?

wessex101 · 4 Jul 2019

Sounds more like a goal post frame rather than wind posts. It depends on how much wall you will have left either side of the new opening and whether your house is detached, terraced etc.

Some structural engineers do seem to get rather carried away, you could get a second opinion from another engineer but someone will have to come up with a design, you cant just take the word of the architect or a bunch of random strangers.

Gav T · 4 Jul 2019

Thanks for your input Wessex. Its a detached house and there will be 1000mm of wall one side and around 2500mm of wall the other side of the bifolds. Just had an email from the SE which says we wouldn’t need windposts if we opted to use 440 x 440 piers made from engineering bricks rather than 440x215 padstones. He won’t answer any more questions now without charging which I think is terrible. For my own sanity, can anyone tell me how the engineering brick pier would be connected physically to the existing brickwork? Would it be tooth bonded?

wessex101 · 4 Jul 2019

Nope, that's got me baffled. Tony is the resident structures expert maybe he can shed some light on it?

Gav T · 4 Jul 2019

Any ideas Tony?

^woody^ · 4 Jul 2019

With that much wall under each bearing, wind posts are not required.

If you have paid this engineer for the design work , then he must have done a calculation on the wall as is to determine that it would fail and thus wind posts would be needed. It would not be unreasonble for this calcualtion to be provided.

Unless, he went staight to the wind post calculation .....

rssteve · 4 Jul 2019

If the original design which you said you submitted to building regs, showed no posts, and the builder is following those plans, does it really matter what the engineer is now saying to do?

Gav T · 4 Jul 2019

Hi woody. The actual amount of beam which sits on the pier at each side will be 250 mm but there’s alot of wall either side as stated above. There’s actually another room to the left hand side of the bifolds on the ground floor. The SE said it was to do with wind against the size of the bifolds (5.5m) But it’s not a windy back garden. This got me thinking that the windposts had been recommended due to the overhanging weight of the bifolds when open.

Can anyone help with my query of how the engineering brick pier will need to be bonded to the existing bricks?

Thanks for everything so far

Gav T · 4 Jul 2019

Hi steve. I get what you are saying about the building regs and the original calcs but if problems occur later in life then who will be liable? Not the SE as he has further recommended windposts (at a later stage) the engineering brick pier at 440 x 440 gets me out of this though which is good. Just need some advice on how the engineering brick pier is bonded to the existing brick work???

^woody^ · 4 Jul 2019

Gav T said:
Hi woody. The actual amount of beam which sits on the pier at each side will be 250 mm but there’s alot of wall either side as stated above. There’s actually another room to the left hand side of the bifolds on the ground floor. The SE said it was to do with wind against the size of the bifolds (5.5m) But it’s not a windy back garden. This got me thinking that the windposts had been recommended due to the overhanging weight of the bifolds when open.

Can anyone help with my query of how the engineering brick pier will need to be bonded to the existing bricks?

Thanks for everything so far

The idea of posts is to reinforce the walls at the side of the opening. Nothing to do with the doors, but normally to do with how much wall there is either side of the opening - ie not enough wall means posts required. But the amount of walls you mentioned is more than enough.

John D v2.0 · 4 Jul 2019

I know everyone is assuming goal post moment frame but to me if it really is wind posts it Sounds like he is worried the wall will crumple/fold over or something. If there is a very long wall with no returns (other walls at right angles) then the whole wall could fall. Is this a full cavity wall or something narrower? Are there any returns?
We had to have wind posts on four 50mm thick internal walls as it needed to hold up part of the roof.

Gav T · 4 Jul 2019

HI John. There is around 750mm of existing brickwork/wall, on the inner bricks, either side of the opening/bifold doors. Then one side comes to a internal wall, which is stud, then the other side comes to the external side wall of the house. Again, the SE has come back to say don't bother with the windposts as long as we build the 440 x 440 piers from engineering bricks, which apparently provide more lateral support to the masonry?

tomfe · 4 Jul 2019

Single or 2 story?
Sounds fine to me without windposts. I've seen many an extension without them and with 750 returns.
Not sure what's been speced but £750 seems high.
You will kick yourself if you have piers and wish you just spent the extra.

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