Catnic Linels or UB with welded plate for longer spans (3.5 and 4.5m)?

[kingandy2nd]

Hey folks,

I'm in the process of building my garage with regular cavity walls, but I'm thinking ahead to the steels above the openings.

I have a 3.5m span at the back for a bi-fold door and a 4.5m span at the front for the garage door opening. I'm going to have one course of blockwork above the steels and then it will be supporting eves of the vaulted roof with concrete tiles. (The gable walls on either side will have a UB at ridge level).

It seems that Catnic do lintels, like this one which seem to be suitable for the spans: https://condell-ltd.com/ig-lintel-l5-100-3900mm

Deflection is 0.003 of span, so I work that our to be around 10mm which should be ok for a bi-fold door.

On my previous extension we ended up with a very heavy steel with a welded plate to carry the brickwork over a similar length, which was a mare to fit due to the weight.

Presumably these catnic's must be up to the job or they wouldn't be available? Or should I put on my big-boy pants and get an SE to do the calcs on some proper steel and just accept there's going to be some heavy lifting involved?

Thanks all

 

[freddiemercurystwin]

I don't know if they still do but Catnic used to provide a design service, where if you provided the loads etc and it fit within their standard formulas they did the calcs and specified a lintel (and sent you the paperwork to shove under the BCO's nose if required) but like I say not sure they still do but might be worth a ring. Using a steel beam & the cost of a cheap SE's services may cost less than a pair of Catnics. For a 4.5m span I'd think it'd be something like a 203 beam or maybe less. Do you not have an SE on board already for the ridge beam?

 

[noseall]

Hey folks,

I'm in the process of building my garage with regular cavity walls, but I'm thinking ahead to the steels above the openings.

I have a 3.5m span at the back for a bi-fold door and a 4.5m span at the front for the garage door opening. I'm going to have one course of blockwork above the steels and then it will be supporting eves of the vaulted roof with concrete tiles. (The gable walls on either side will have a UB at ridge level).

It seems that Catnic do lintels, like this one which seem to be suitable for the spans: https://condell-ltd.com/ig-lintel-l5-100-3900mm

Deflection is 0.003 of span, so I work that our to be around 10mm which should be ok for a bi-fold door.

On my previous extension we ended up with a very heavy steel with a welded plate to carry the brickwork over a similar length, which was a mare to fit due to the weight.

Presumably these catnic's must be up to the job or they wouldn't be available? Or should I put on my big-boy pants and get an SE to do the calcs on some proper steel and just accept there's going to be some heavy lifting involved?

Thanks all

If the roof pitches down over the beam, have you checked whether you actually need to carry ANY outer leaf masonry?

 

[kingandy2nd]

I don't know if they still do but Catnic used to provide a design service, where if you provided the loads etc and it fit within their standard formulas they did the calcs and specified a lintel (and sent you the paperwork to shove under the BCO's nose if required) but like I say not sure they still do but might be worth a ring. Using a steel beam & the cost of a cheap SE's services may cost less than a pair of Catnics. For a 4.5m span I'd think it'd be something like a 203 beam or maybe less. Do you not have an SE on board already for the ridge beam?

Good shout FMT. It's not really a cost thing for me, it's more for ease of fitting as these catnics appear to be less than 100kg. On my extension the garage beam was a similar span and was a 152 x 152 x 30 with a 250 x 8m plate and it was a bugger to move

I've not yet got an SE for the ridge beam. Are you taking on work at the moment Freddy?

If the roof pitches down over the beam, have you checked whether you actually need to carry ANY outer leaf masonry?

The garage is going to have a car lift in it, so I'm looking to maximise the height. Garage door will be 2.1m and I want to get the wall plate up to around 2.4m so a row of blocks will be the way to go I think.

Thanks both for the quick replies

 

[noseall]

The garage is going to have a car lift in it, so I'm looking to maximise the height. Garage door will be 2.1m and I want to get the wall plate up to around 2.4m so a row of blocks will be the way to go I think.

2.4 is pretty standard.

With this recent job...

hip1.jpg

• noseall
• 25 May 2025
• 1

hip3.jpg

• noseall
• 25 May 2025

The wall plate was about 2325mm above DPC. Door/window heads standard 2.1m The roof pitch was fairly shallow, yet it was enough of a soffit overhang/pitch-drop that the soffit actually finished at window/door head height, i.e. no outer leaf masonry required.

 

[kingandy2nd]

2.4 is pretty standard.

With this recent job...

hip1.jpg

• noseall
• 25 May 2025
• 1

hip3.jpg

• noseall
• 25 May 2025

The wall plate was about 2325mm above DPC. Door/window heads standard 2.1m The roof pitch was fairly shallow, yet it was enough of a soffit overhang/pitch-drop that the soffit actually finished at window/door head height, i.e. no outer leaf masonry required.

Thanks for sharing.

I like the look but I’m playing with a 17.5 roof so as shallow as shallow gets.

Is that garage door 2.1 high too? I would really like a flush roller door to the from like that one in your picture, but with the roller in the opening you loose 20-30mins so I’d be ducking to get in it.

 

[noseall]

I like the look but I’m playing with a 17.5 roof so as shallow as shallow gets.

Oh. That is shallow.

Is that garage door 2.1 high too?

Yes, but as you correctly state the roller bulk eats into the height.

I would really like a flush roller door to the from like that one in your picture, but with the roller in the opening you loose 20-30mins so I’d be ducking to get in it.

Can you not have them fitted so that the roller is tucked away on the inside of the masonry, i.e. behind the lintel?

 

[Murdochcat]

Why would you go to the expense of bi fold door in a garage ?

 

[kingandy2nd]

Oh. That is shallow.

Yes, but as you correctly state the roller bulk eats into the height.

Can you not have them fitted so that the roller is tucked away on the inside of the masonry, i.e. behind the lintel?

Yeah, my plan is to have the roller fitted on the inside of the opening - which in thinking about it - is also another reason for needing a bit of height with the a row of blocks on either skin.

I would have preferred to have it like your job, as you then get a little bit more room inside. Your job’s way looks way nicer too

 

[kingandy2nd]

Why would you go to the expense of bi fold door in a garage ?

Got it cheap on eBay, so why not

 

[freddiemercurystwin]

@kingandy2nd I'm no SE, @tony1851 might assist if you PM him, he'll thank me for that! Or I think @RonnyRaygun is an SE but not sure he posts much these days either.

 

[kingandy2nd]

Tony's been great and has helped me in the past. I hadn't seen him round too much lately so didn't want to trouble him.

 

[noseall]

Yeah, my plan is to have the roller fitted on the inside of the opening

The one downside I can see with that though is rain striking the rather broad projecting toe.....

It could become a nuisance.

 

[noseall]

Why would you go to the expense of bi fold door in a garage ?

I put french doors on my shed.....

shed.jpg

• noseall
• 4 Dec 2022