Options for shed roof ties?

[Ivor Windybottom]

Mortar has approximately zero strength on day two, it takes a week to be much more than damp sand. I could probably get away with non-hammer drilling into mortar rather than brick, but then the wall plug might spin or pop the mortar out when it expands.

I'll have a play with the sample bracket, see how terrible it would be to build it in.

As stated above, I can pop some screws into mortar beds above if it needs some anti-waggle support. Not to take its weight, just to help hold it up until it's screwed into the wood. But if it's ultimately just between the roof structure and anchored very firmly into one brick joint about 10 courses down then that should be pretty good, and a lot better than nothing.

 

[Mr Chibs]

I'll be honest, I never drill into mortar unless it can't be helped.
I'd concrete screw straight into brickwork, but I'm sure your way will work.

 

[Ivor Windybottom]

I bought the representative (non-twisted) bracket from Toolstation for £2-odd.

It gets held upright absolutely fine by just standing a brick on its tail. But I've yet to find out for terrible it is once there's wet mortar against it rather than just brick.

More experiments will be carried out shortly.

 

[Ivor Windybottom]

My latest idea is that I'll stand the bracket on top of a perp joint, and tap a couple of nails through it into the partially set mortar below. Then mortar, then the brick above...

It will be held down by the brick above. The nails into the perp joint are just to pin it into place while the mortar above it sets, to stop it falling over.

This does mean they need to go on a perp joint so will dictate where the roof joints go, and at 450mm spacing (2 bricks). But I think I can work with that.

If any of the holes below the twist happen to align with a bed joint then I'll jam a nail in there too.

But above the twist it will just be flapping about. I'm thinking this could be an issue, it will stop the roof lifting but there won't be much resistance against it sliding sideways.

 

[Mr Chibs]

Is this only going to be attached one course down from the wall plate?

Isn't the point of restraints is that you are anchoring to a the wall 1m down, you are adding lots of weight for the straps.

 

[Ivor Windybottom]

Is this only going to be attached one course down from the wall plate?

Isn't the point of restraints is that you are anchoring to a the wall 1m down, you are adding lots of weight for the straps.

They're 900mm tall, so would be 75mm x 10 courses down, leaving 150mm sticking out of the top to screw onto the sides of the joists.

I can't have a wallplate due to height restrictions of permitted development.

I hope they'll be OK, perhaps with brackets into the top course to resist the sideways forces...

Unless anyone else has a better idea for invisible roof ties? I'm surprised there isn't something designed for the job. I've seen some american thing where they put a thick rod in as a wall tie then hook onto it with a hooked rod from the top. This avoids having the thing flapping about while building, but it ends up with the same thing.

 

[Mr Chibs]

Sorry was commenting on your 'new' idea... not the old one. As per the yellow brick drawing.

 

[Ivor Windybottom]

Sorry was commenting on your 'new' idea... not the old one. As per the yellow brick drawing.

It's all the same idea, the only new bit is nailing down into a perp joint to (hopefully) stop it falling over. The previous drawing just didn't show the full length, the second drawing does.

I'm still hoping someone's going to tell me the proper way of doing it!

 

[George_engineer]

I thought the plan was to build the inner leaf wall up ahead of the outer leaf and use a regular twist tie positioned in the cavity.

There's no need to build the tie into the wall.

 

[OvertonPlumber]

If you do use wall straps they have to be heavy duty 3mm thick building regs compliant not this thin crap.
When we did our trussed roof replacement we strapped every 1.2mtr internally. I also used 50x 460mm facade concrete screws through my wallplates into the existing concrete blockwork.
May seem overkill but my trusses weighed 2.2 tons plus the tiles.

 

[Ivor Windybottom]

I thought the plan was to build the inner leaf wall up ahead of the outer leaf and use a regular twist tie positioned in the cavity.

There's no need to build the tie into the wall.

I was worried about the risk of drilling into a single-brick untied newly built wall, hence the idea of building in one that has both a twist and an angle. I don't know how real a risk this would be, but I'd be really sad if I put a massive crack into a brand new wall and have to pull it down and start again.

But the issue is that most of the tie will be at right angles to the wall, not flat against it. I won't be able to screw in most of its length so it will be able to bend sideways. So it would resist lifting but wouldn't resist sideways movement very much. This is why I added the bracket to the left of my joist in the doodle above.

I will try bending a wire wall tie in half over the strap and building it into the wall higher up, to give some extra sideways support, kind of like a staple...

The building is only about 4m x 5.5m, with a timber/rubber sheet flat roof. It will be lightweight, which is actually a bad thing. That 2.2 ton +tiles roof above is not going anywhere in a storm, your ties are needed to keep the building inspector happy but will probably never actually do anything, the weight of the roof is really all that's needed. I don't think our 1950s bungalow's tiled roof is held on by anything other than gravity, and it's definitely still there after 70 years including a few great storms. But my light flat roof is definitely capable of being lifted.

I don't have building control involved at all, this is just a permitted development shed so I can do what I like really. I'm happy that the lightweight straps will be adequate, I could fit them every 450mm (2 bricks) and space the joists accordingly. The lighter weight will make them less annoying to build in, and a bit of bendiness could be handy if they end up a bit misaligned. I don't have enough height for a wallplate (due to PD 2.5m height limit).

But... I really hope there's a proper way of doing this, other than having metal straps visible inside the room. Do all industrial buildings really have visible straps?

 

[Ivor Windybottom]

I think I've answered my own question - most industrial units have a streel frame, the roof is attached to the frame so it doesn't need tying to the wall...

So my idea of having an unplastered wall that's structural is actually fairly unusual, so this would be why most builders don't have this issue.

But I'd still like to avoid having metal straps all over the inside of the room.

 

[George_engineer]

I was worried about the risk of drilling into a single-brick untied newly built wall, hence the idea of building in one that has both a twist and an angle. I don't know how real a risk this would be, but I'd be really sad if I put a massive crack into a brand new wall and have to pull it down and start again.

But the issue is that most of the tie will be at right angles to the wall, not flat against it. I won't be able to screw in most of its length so it will be able to bend sideways. So it would resist lifting but wouldn't resist sideways movement very much. This is why I added the bracket to the left of my joist in the doodle above.

I will try bending a wire wall tie in half over the strap and building it into the wall higher up, to give some extra sideways support, kind of like a staple...

View attachment 307956

The building is only about 4m x 5.5m, with a timber/rubber sheet flat roof. It will be lightweight, which is actually a bad thing. That 2.2 ton +tiles roof above is not going anywhere in a storm, your ties are needed to keep the building inspector happy but will probably never actually do anything, the weight of the roof is really all that's needed. I don't think our 1950s bungalow's tiled roof is held on by anything other than gravity, and it's definitely still there after 70 years including a few great storms. But my light flat roof is definitely capable of being lifted.

I don't have building control involved at all, this is just a permitted development shed so I can do what I like really. I'm happy that the lightweight straps will be adequate, I could fit them every 450mm (2 bricks) and space the joists accordingly. The lighter weight will make them less annoying to build in, and a bit of bendiness could be handy if they end up a bit misaligned. I don't have enough height for a wallplate (due to PD 2.5m height limit).

But... I really hope there's a proper way of doing this, other than having metal straps visible inside the room. Do all industrial buildings really have visible straps?

Twist ties are a thing. They have a 90 degree twist 100mm from the end.

Simpson Strong-Tie Heavy Twisted Restraint Straps | London | Hertfordshire

Heavy duty restraint straps made from 30mm x 5mm galvanised edge coated steel for lateral restraint of roof trusses, rafters and joints tied into masonry walls.

www.metrofixings.co.uk

You'd need to leave the mortar to cure (min 24 hours, leave another 24 to be sure) but just use a diamond drill bit so you don't need the hammer action if you're concerned about the wall. Concrete blocks are pretty robust.


Slightly OT, but have you considered using fair faced blocks - that is, concrete blocks with a more refined finish.

Fair Face Blocks from Mannok

Paint Grade Fair Face Blocks Our Paint Grade blocks from Mannok's quarries are suitable for all types of wall construction, including internal and external cavity leaves and partition walls and are commonly used in commercial buildings such as factory units, shops and offices. They offer a...

www.mannokbuild.com

 

[Ivor Windybottom]

Twist ties are a thing. They have a 90 degree twist 100mm from the end.

Simpson Strong-Tie Heavy Twisted Restraint Straps | London | Hertfordshire

Heavy duty restraint straps made from 30mm x 5mm galvanised edge coated steel for lateral restraint of roof trusses, rafters and joints tied into masonry walls.

www.metrofixings.co.uk

You'd need to leave the mortar to cure (min 24 hours, leave another 24 to be sure) but just use a diamond drill bit so you don't need the hammer action if you're concerned about the wall. Concrete blocks are pretty robust.


Slightly OT, but have you considered using fair faced blocks - that is, concrete blocks with a more refined finish.

Fair Face Blocks from Mannok

Paint Grade Fair Face Blocks Our Paint Grade blocks from Mannok's quarries are suitable for all types of wall construction, including internal and external cavity leaves and partition walls and are commonly used in commercial buildings such as factory units, shops and offices. They offer a...

www.mannokbuild.com

Thanks, I was assuming that drilling into a newly built single skin wall was pretty risky. I like your idea of the diamond bit, I'll try drilling a tile (spade) bit into one of the bricks, see how it goes.

I've got the bricks already, they're a yellow coloured concrete brick. I just wanted something smoother and lighter coloured than block, mainly so I don't have to paint it but also so it will stand up to getting bashed about. These in fact...

Islington Stock Buff/Cream Facing Bricks

Islington Stock Buff/Cream Facing Bricks from Marshalls. Solid, robust & frost resistant blocks now available from the impressive Sandstock collection.

www.marshalls.co.uk

They're a bit weird looking but nice and bright, non-dusty and were cheap, 30-odd pence each so a similar price to block (1 block = 6 bricks). Obviously it's more effort for laying, but I'll cope.

Some of the modern blocks I've seen seem like they're hardly held together, almost like polystyrene.