Support a chimney stack with a wooden lintel? (please read)

[tombodge]

Hello. Please give me a chance to ex-plane myself and look at the pictures. Im not a complete idiot but I could really do with some advice on this.

I know the chimney removal thread gets repeated all the time.

But the situation i'm in is this.

I got a structural engineer in to do calculations for a load bearing wall ive removed and also got him to sort me a spec for the gallow brackets at the same time. He didnt take any measurement for the chimney. Just said ive got a spec for that and gave me a generic spec for gallow brackets on a piece of paper with his company letter head on the top of this.

I sent all this off the building control along with my fees and wall calculations which they said was fine.

Ive come to drill the holes for the M20 bolts (stupidly over speced imo) and from all other gallow brackets ive seen.

24mm wet core bit, blue engineering brick 170 deep 3 brackets. 9 holes. its taking 3 hours per hole!!!!!!!!!

that's 3 solid days drilling without taking breaks into account.


What would everyone do that's more exsperanced than me? Im a true DIYer.


What I want todo is the same as what the next door have done.


Its a split chimney stack. 2 stacks join in the roof then leave the roof as one.

Next door have removed the same stack and me and have left the other stack in place. Which is what im doing.


I want to remove some bricks from the other stack to install a very large (8x4) wooden timber to then fix onto the main (large) roof purlin via a joist hanger.

I no its possible as next door have had it done but is it safe or not recommended

Is building control going to have a paddy over it?


How would everyone work around this situation. Im guessing no one would spend 3-4 soild days drilling??


Ive added pictures

 

[tony1851]

As long as the span of the 8x4 is not excessive, it's perfectly OK to suspend it off the end of the purlin.

Doubtless the usual crew will be along soon to say you can't do that, and the building inspector may well throw his dummy out. However, it's safe to do this and can be proved by calculation.

 

[tombodge]

Hi tony,

thanks for the help. Is this the route you would go down instead of drilling the holes and installing the brackets?


The length of the timber is 1.9M.


Ideally Id need to install the timber below that purlin as to keep the same courses of brick inside the loft space as it above the roof as recommended. Also if i install it so its buts upto the roof purlin then its getting quite close to the roof line, not that i think it will be a problem

 

[tony1851]

Look - nine 20mm diameter bolts embedded 170mm to support a few bricks is not engineering - it's lunacy. Think about how all that drilling will shake the bricks loose!

Get your 8x4 supported off a heavy-duty hanger on the purlin and that will do.

(As an example of how these things can be supported, see this pic, where a small angle iron runs under the chimney breast (in this case just above the ceiling); the far end is supported off an existing beam, and the near end is supported by a vertical angle, in turn bolted to the side of the purlin).

Untitled

• tony1851
• 18 Nov 2014
• 2

 

[tombodge]

cheers tony.


Im all up for doing it this way. My only concern is if building control don't like it and want me to change it.

Are they going to be happy if tell them ill get calculations to prove its ok. It will be a right pain in the arse to change it after ive put my ceiling back up.


I cant really think of a way to use a metal rsj eather.


Are they going to say i cant use wood because of fire risk or rot? Although my house is filled with wooden lintels (1920 house) all nearly 100 years old and there all 100 % rock solid and sound.

Can they "make" me change it.


As far as building control are concerned they seem to want ether gallow brackets or a metal rsj with 30 minutes fire resistance (unless fully within the roof which mine is) i got that from google

 

[tombodge]

I could just do it and cross my finger that my building inspector is sound, knows himself that its safe and is happy to sign it off.


If I just explain why Ive done it he might be reasonable and let it pass.

My BC wasn't interested in calculations to support the gallows. and they didn't ask if next doors had been removed.

In my mind a beam (been metal or decent sized wood) is a much better solution to gallow brakets.

To add to this my house is built with lime mortar which is in a poor condition on this wall inside the loft (im going to repoint it as some point)


worse case they can give me a solution and ill have to change it at a later date. Id rather do that than spend a week drilling holes.

 

[oldbutnotdead]

3 hours per hole- that's v dull.

Try giving Building Control a ring- explain what the sketch is (stock gallows brackets from mad engineer, taking forever, mortar rattling out of joints), explain your new masterplan and see what they have to say. Worst possible case is you'll have to keep drilling holes....

 

[tony1851]

Are they going to be happy if tell them ill get calculations to prove its ok. It will be a right pain in the a**e to change it after ive put my ceiling back up.

If you get calcs to prove it is OK, to the satisfaction of their own engineer, they have to accept it.

 

[tombodge]

3 hours per hole- that's v dull.

Try giving Building Control a ring- explain what the sketch is (stock gallows brackets from mad engineer, taking forever, mortar rattling out of joints), explain your new masterplan and see what they have to say. Worst possible case is you'll have to keep drilling holes....

They could be very helpfull but i have a feeling they would probaly ruin my day.

Id rather spend the 2-3 hours installing this wooden beam and argue the toss over it for as long as possible and then if I really have to spend 5 days drilling holes ill do it at a latter date.... like 1hour a week

My thinking is ive got more chance of doing it this way if i just do it rather than ask if i can do it lol

 

[tombodge]

Are they going to be happy if tell them ill get calculations to prove its ok. It will be a right pain in the a**e to change it after ive put my ceiling back up.

If you get calcs to prove it is OK, to the satisfaction of their own engineer, they have to accept it.

sweet im going to go for it. Its actually a 4x7 timber ive got but it seems more than big enough.

Thanks again for the help

 

[unclebob1]

Just a thought but have you considered removing the whole stack? You said your neighbor has already supported their side, and I'm assuming you are in the process of removing your stack... how about remove the whole lot and replace it with a "Fake one" on the outside for appearances? (with permission from next door as well as council?)

 

[tombodge]

Hello. We are both keeping the stack in the front room which share the same chimeny coming out of the roof it that makes sence. Probaly would have been easyer to remove the lot though

 

[unclebob1]

Apologies - thought both parts of the stack were coming out!

Though some of the fake ones can be actually used - they need to be lined i think!