Timber frame garage door lintel (or is it!)

[Sam187]

Evening all.

I am in the process of constructing a timber frame double garage as it is over 40m2 it requires building regulations.

The frame is 100x50 c16 construction and will have a traditional rafter roof covered with box profile steel sheet.

My question is in relation to the lintel over the double door. The unsupported span is 3.7 meters.

My original plan was to use 2x 200x50 bolted together which I think would be sufficient (I spoke to the builder who dug my foundations and laid my concrete who agreed)

Today I have had a wobble in the confidence of their suitability re building regulations. The door is in the gable and the building is timber clad so the only thing above the lintel is the cladding to the ridge which pretty much makes the lintel non load bearing.

I will contact building regulations early next week but I would like to crack on tomorrow!

Basically, in your opinion are 2x 200x50's suitable for this application?

Many thanks

Sam

 

[John D v2.0]

when it comes to opinions, you want to listen to structural engineers not anyone else.
Howver having said that it would undoubtedly be strong enough from what you say.
In terms of deflection that would be a matter for what doors you plan to use.

 

[Sam187]

Thanks John,

I do understand opinions are like backsides...

I plan to fit barn style doors (so hinged to the vertical frame)

Sam

 

[John D v2.0]

There are lots of other things to take into account, if each door is nearly 2m long and presumably heavy, what happens if one door is fully open and the other closed? Or both doors open 90 degrees? There will be a lot of forces on the structure other then just dead loads, also wind and other variables loads. You would need to take care. Masonry there are standards for returns and pillars, probably have the same for timber constructions.

 

[Sam187]

There are 225mm square pillars either side of the opening to give extra rigidity. Brick for 3 courses and then timber above.

Sam

 

[Leofric]

There are 225mm square pillars either side of the opening to give extra rigidity. Brick for 3 courses and then timber above.

If you have a timber clad timber frame building why are you introducing a bit of bwk , but the above description doesn't seem to make sense anyway

 

[Sam187]

If you have a timber clad timber frame building why are you introducing a bit of bwk , but the above description doesn't seem to make sense anyway

The whole timber frame sits on a 3 course brick dwarf wall to keep the timber frame out of any water.

The double door opening has 225 x 225 piers either side. These are 3 courses high in brick and then above that is timber frame.

 

[Leofric]

The whole timber frame sits on a 3 course brick dwarf wall to keep the timber frame out of any water.

The double door opening has 225 x 225 piers either side. These are 3 courses high in brick and then above that is timber frame.

Oh, I see now. Don't forget the dpc.

 

[Sam187]

Oh, I see now. Don't forget the dpc.

Thanks Leofric, already in the plan!

 

[^woody^]

With a timber frame building, the load is taken by the frame, and any brickwork is just cladding. So the reference to brick piers, including any at the base is irrelevant for loading.

As for the question, the BCO will want likely want calcs to justify the beam, and the frame design too in terms of rigidity and loading, among with the normal resistance to damp and fire performance.

Even without any information on the loadings or bracing, 2x 50x200 don't seem adequate for a 3700 span.

 

[Sam187]

With a timber frame building, the load is taken by the frame, and any brickwork is just cladding. So the reference to brick piers, including any at the base is irrelevant for loading.

As for the question, the BCO will want likely want calcs to justify the beam, and the frame design too in terms of rigidity and loading, among with the normal resistance to damp and fire performance.

Even without any information on the loadings or bracing, 2x 50x200 don't seem adequate for a 3700 span.

Agreed - the reference to the piers was to demonstrate a widening of the frame at the door aperture.

The frame is built at 400 centres which I believe to be on the more robust side.

When speaking to the BCO last time I saw them they weren't bothered about seeing anything else until the roof is on .
I will check with them when they are back after the holidays before going any further.

Sam

 

[Leofric]

If it is a traditional roof with purlins they will be supported by the gable timber frame which may transfer the roof load to the beam over the door opening.
Something to consider.

 

[Notch7]

The frame is built at 400 centres which I believe to be on the more robust side.

What is the frame clad with? Does it have sheathing ply?

Stud framework needs bracing for lateral stability, imagine a 100 mile an hour wind on the side of the building.

 

[Sam187]

If it is a traditional roof with purlins they will be supported by the gable timber frame which may transfer the roof load to the beam over the door opening.
Something to consider.

Thanks - I will bare that in mind.

What is the frame clad with? Does it have sheathing ply?

Stud framework needs bracing for lateral stability, imagine a 100 mile an hour wind on the side of the building.

The studs are braced with noggins. The frame will be clad with steel box profile on two walls and 20mm feather edge on the other two. Internally it will be lined with plasterboard.

Thanks

Sam

 

[^woody^]

The frame will be clad with steel box profile on two walls and 20mm feather edge on the other two. Internally it will be lined with plasterboard.

That does not seem adequate for racking resistance of the frame. It would normally need at least an 11mm board of some sort on the external face.