Lintel above garage door

Discussion in 'Engineers' Talk' started by Aaron Mcculla, Oct 25, 2022.

  1. Aaron Mcculla

    Aaron Mcculla New Member

    Hi, I'm in a predicament with what lintel to put above a garage door, im currently building a 5.75 x 6.60 metre garage out of 6 inch solids, the span of the door is 4.4 metres. Walls approx 2.3 high, max 4 metre to apex roof. Above the garage door will be cladded with cement board rather than be load bearing like blocks. In my opinion the lintel needs to support the door which I've enquired is 80kg and the weight of the timber frame and cement board cladding.
    Rather than have the expense of a RSJ which I believe will be overkill . Would 2 8x2's bolted together be sufficient?
    Many thanks
    Aaron
     
  2. Hausfix

    Hausfix Screwfix Select

    I’m making the assumption that you’re building this without the input from your local building control officer, as they would be able to provide the definitive answer based upon the circumstances.
    However, I’ve yet to come across any garage door that is supported by the lintel spanning the structural opening. The load of the door will be transferred to ground through the vertical frame either side, or in the case of a roller door, the brick piers either side.
    It sounds like a Catnic type steel lintel is what is needed here, possibly a T9 steel “ L shape” lintel as an alternative. Either will be resting on a suitable brickwork pier at each end.
    An “RSJ” would be overkill for certain. It’s impossible to give the correct solution based on your description alone, but under certain circumstances, a lightweight timber frame with cladding above could very well be supported by two timber joists, sistered with a steel flitch beam in between to avoid deflection once the weight of the roof is applied. You’ll need to take into account snow loading and the force of heavy wind conditions when making the calculations.
    I’m not saying the pair of 8”x 2” won’t be sufficient, but it would be better to seek the opinion of an expert who can visually inspect what you have built and give advise based on what they see. Taking the opinion of a forum member isn’t especially wise when it comes to structural engineering solutions.
     
    Last edited: Oct 25, 2022
  3. Aaron Mcculla

    Aaron Mcculla New Member

    Hi Hausfix, thankyou for the speedy reply. Yes there is no Input from building Control as this will fall within permitted development as the Internal floor space will be less than 30m2. But non the less it needs to be structured sound and if any inspection was required I would like to meet all standards.
    I believe the timber would be more than adequate but like you say deflection / bowing would be my main concern. I will definitely look into a steel flinch beam.
    I would like to overengineer if there is such a thing as my property is on top of a hill and very exposed to frequent heavy winds.
    Thankyou for your knowledgeable answer :)
     
    Hausfix likes this.
  4. Hausfix

    Hausfix Screwfix Select

    If you go with the timber option, my feeling is that you’ll end up with a better long term result by adding plenty of noggins to connect it to the joist work behind it. This will help to control it bowing outwards in addition to whatever method you use to mitigate downwards flexing.
    Be careful if your permitted development only allows a maximum of 30m2 internally, as your dimensions suggest you will end up with over 34m2 with a 150mm thick single skin block wall!
     
  5. Aaron Mcculla

    Aaron Mcculla New Member

    OK thankyou for your input, much appreciated.
    I know it has ended up slightly bigger than I'd anticipated. I may have to stud the wall out to comply within permitted development.
     
    Hausfix likes this.
  6. Hausfix

    Hausfix Screwfix Select

    Best of luck and hope it all goes to plan. Let us know what you ended up doing when the project is completed.
     
  7. adgjl

    adgjl Screwfix Select

    Permitted development relates to there being no requirement for a Planning Application. It does not necessarily mean there is no requirement for Building Control, which is a different process.
     
  8. damtomuk

    damtomuk Member

    Exactly. He will still need building control application and certificate on completion, without this house might be unsellable
     

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