Lintel size for garage door

[Hoggy26]

Hi all
I'm completely uneducated in civil engineering of any sort so please forgive my ignorance.

I'm having a large garage built with doors measuring 2.7 meters wide and 2.7 meters high, with roller shutter doors fitted.

The lintels the builder has fitted are concrete pre stressed 75mm (3inch) thick and are supporting one course of concrete block above them. The roof will be made of that corrugated plastic so NO heavy tiles etc.

Are these lintels adequate as a number of people have expressed concern?

Many thanks in advance.

 

[Hoggy26]

 

[Hoggy26]

 

[r1flyguy]

I would hazard a guess that they are designed to be strong enough to span that distance dependant on the weight they are supporting by which youve explained isnt much. They should also contain rebar so they aren't going to crack and fall.

The one we removed from our garage was a box section steel lintel so have no comparison

Quick google with give you design strengths if you want some reassurance. Im sure there are a few lads on here that will be able to advise you better

https://stowellconcrete.co.uk/precast-concrete-lintels/

 

[^woody^]

They will be OK

 

[Tigercubrider]

Completely non qualified opinion but...

Would they actually make something that long if it couldn't support a load ?
I guess that the blocks above would represent the minimum they might expect?

Plastic roofs aren't exactly secure and roller doors are expensive .
Presumably what you will store is worth security

 

[Hoggy26]

Thanks gentlemen I appreciate the advice.
I've gone for roller shutter doors due to the height I need to get a 4x4 in with roof rack and kit etc (2.7meters)
Up and over doors at this size are hard to come by.
The not very secure plastic roof is a weakness I must admit but it's 3 meters high and is in my back garden in a built up area as oppose to a lock up in the middle of no where so I'm hoping that will be enough of a deterrent.
I know no matter what I do, if they want to get in they will but any more advice in this area is also appreciated. (obviously getting an alarm fitted)

 

[^woody^]

You could have a layer of ply below the sheets for security

 

[oldbutnotdead]

The pond life might get in through the plastic roof but if they want to take any swag with them they'll be wanting to leave via the doors. Sooooo-
If there's a personnel door, make sure it is solid and has a decent lock in it
Roller door- don't fit the manual override (or if you do, make sure it is lockable)
Roller door- (assuming electric)- interlock it with your alarm so if alarm is set or is triggered there is no power to the door motor (relays are required)
If you're having an alarm, put a proper mag contact on the roller door
If you're having an alarm, get one that'll send you text messages or phone you up if anything happens (rather than a noisy bell that everyone will ignore)
If you can live with the hassle, fit a big bar across the main doors (internally obviously) with good locks holding the bar in place (so the pond life can't drive out in your precious)
Keep the main doors shut EXCEPT when you're arriving/departing (so passing pond life can't see there's anything worth having)