So, I'm building a bit shed. It's made out of 4x2 and clad in 19mm waney edge oak. It's approximately 8m x 4m with a pitch Onduline roof.
It has a double garage door at one and and somehow I've failed to put in a lintel over the opening. At first there was no problem but when I came to clad the gable in oak, the timber above the opening sagged and is now preventing the doors from opening and closing properly. It's currently propped up with a bit of 3x2 which you can see in the second picture.
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the question is, what can i do to support the opening? A big bit of timber (8x2?) screwed on? Angle iron? I can't bolt through as the oak is in the way and I REALLY don't want to take it off.
Get a substantial piece of timber (8x2" or 6x2) or long plat of sheet steel, jack the opening up with a couple of acrows and bolt the support across the back of the door, overlapping both sides of the door as far as possible - maybe the full width of the garage.
Bolt through the frame over the opening and the vertical struts just above and to all the wood to each side that the plate crosses - at least to the 2 full height verticals each side of the door or even to the corner ones if accessible from inside.
If sheet steel is a pain to get, you might be as well off with a steel box lintel from the builders merchant.
>>> So the question is, what can i do to support the opening? A big bit of
You could glue it too for extra strength - PU foaming wood glue (eg Gorilla) would work well, but PVA would probably be OK as the wood is smooth - just make sure to use the waterproof version.
It doesn't look to me as if you would need a lintel on that kind of construction and with a light weight roof. Is it possible you have simply distorted the frame while knocking in the vertical studs on the gable end? It is easily done. I would be suprised if it is anything to do with sagging under such a small weight. If so ( and I cannot know of course) you may be able to simply remove and refit the three vertical studs just above the head of the door frame to bring the head straight and level.
I see you have had some other replies. Be very cautious if you are persuaded to use brute force, acrows, big hammer and cargoe straps. It is not good practice to build in extra massive stresses like that. It may work but it may have unforseen consequences. Think carefully first.
Are you going to line the inside? Evenly jack up the undersized bit of wood up so the doors work (couple more bits of 3x2 jammed in like you already have?). Then firmly attach a single picee of decent ply,
12 or better 18mm, that covers the entire area under the large beam above and overlaps the large side supports and the undersized horizontal. By firmy attach I mean No.10 or 12 screws that penetrate
1/2 to 3/4 the thickness of the supporting timbers at no more than 6" centers in tight holes in the ply. It might be worth jacking a bit higher than perfect to allow a little settlement but I doubt 18mm ply is going to move very far. Might be worth extending left/right to the next vertical but that looks to be set further back than the area above the door and think about attaching to the large horizontal as well but I don't think that will be required.
The question you need to ask yourself is why it has sagged. That would help in determining what the best remedial measure would be.
Presumably the struts above the transverse beam shown in the second photo do nothing to support that beam but a simple sturdy angle iron triangle with a single central tie could be inserted in the space above the main beam. (But see later).
A simpler solution is possible with modifications to the horizontal ladder construction between the transverse beam and the bar across the top of the door which are transmitting the deflection in the beam above to the bar below. If the transverse beam has moved as far as it is going to do then shortening the struts between beam and bar and making sure beam and bar are tied together should be enough to restore functionality.
If it was me I would be trying to work out why before starting on remedial work. On the face of it the door pillars mean that section of the main beam could be considered as having built in ends and should deflect very little under its own weight. Ergo it is the struts above transmitting the roof load downward that is the problem. Removing them and replacing with a framework modelled on a modern roof truss might be all that is required. If you want vertical timbers to fit the cladding to the front elevation the roof truss could be set a little back and the verticals nailed to that without actually reaching either beam or rafter. That would have the beneficial effect of further stiffening the truss without loading the beam.
Hmmm, well it's not the three studs above the door because the door was hung after they went in but the studs that form the gable did go in later and could have created the problem. Throuble is, now they've got loads of cladding nailed with 80mm ring shank nails fitted which would be a bu**er to get off.
I think I'll lift the head of the door slightly, fix a sheet of 18mm ply and allow it to sag slightly, then plane the top off the doors
I don't think the roof load is the problem because the doors were fitted after the roof was finished and were fine before the gable and cladding went on. However, your advice to find the cause of the problem before proceeding is valuable. Ta
I agree with that, unless it is due to the roof's weight is not properly supported at either side? It does look very substantial and I would suggest the 3x vertical studs just above the door may need to simply be shortened.
Before you do anything drastic cut through them with a saw, wedging a piece in alongside so the blade isn't pinched when you go through. Take out as much as you need to then fit another stud next to the cut one. Easy.
>>> So the question is, what can i do to support the opening? A big bit of
I've taken quite a few pics of the shed building process and am planning to publish the lot very soon, so why not wait a few days until you see them all, then take your pick?
You could replace the three vertical studs over the opening with a pair of diagonal ones that run from the doubled up uprights at the side to the centre of the door opening at the top. That would transfer any load to the doubled up side supports of the doors and put the thinner beam over them in tension.
There does not appear to be a fundamental reason for a sag though unless those uprights are just a tad too long and as each has gone in its applied a little extra deforming force.
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