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I have a barn/garage attached to the side of the farm house. At the moment it has a wide(ish) door and 2 windows to either side of it. I would like to be able change the front opening to a single one wide enough to fit a car in. Ideally the final open span needs to be 3m wide.
The setup currently looks roughly like this. Not exactly to scale, but you get the idea of roof trusses. The roof is covered in 6" boarding with slate tiles on it. ( Its probably approaching 100yrs old )
[URL= http://img.photobucket.com/albums/v131/donboyfisher/House/Garage%20Roof%20Existing_zpsmhx1gixe.jp g" target="_blank">
http://img.photobucket.com/albums/v131/donboyfisher/House/Garage%20Roof%20Existing_zpsmhx1gixe.jp g"/> [/IMG][/URL]
I am thinking of removing the existing openings and fitting a couple of beams across the span… a bit like this:
[URL= http://img.photobucket.com/albums/v131/donboyfisher/House/Garage%20Roof%20Beams_zpsq5smskbe.jp g" target="_blank">
http://img.photobucket.com/albums/v131/donboyfisher/House/Garage%20Roof%20Beams_zpsq5smskbe.jp g"/> [/IMG][/URL]
I am trying *very roughly* figure out what sort of beam I would be needing to cover this span. My walls are about 40cm thick, made of old stone.
I have a limit on the beam height of about 20cm.
The final opening needs to be 3m wide.
I have about 60cm of wall to seat the beam on one side and at least a metre on the other.
There is no other loading on the beam other than the trusses that hold the roof.
There is no horizontal bracings on the roof trusses that sit on the beam.
(There are horizontal beams going from wall to wall parallel to the front aspect but they are not pictured. They dont touch the roof beams coming down onto the front aspect wall )
Can anyone tell me how I can go about guestimating the loading on the beam? Is there generally accepted values for slate roofing weight in the same way that you get generally accepted loadings for brick wall construction etc.
I would presume it would also be affected by the roof angle and height ?
Even just starters for 10, or the calculations I need to do ( I can do maths … just !)
I don’t mind if 2 beams is complete over-engineering … its more to check at an early stage whether this setup would be possible to achieve within my height restriction of 20cm tall beam across the span. The inner beam if less load bearing would more likely be used to support / brace a pair of large barn doors.
Thanks folks !
Will you need building regulations for this? If so they probably wont accept guesstimates. They will need to see calculations done by someone qualified.
I just had some done for a wall I'm knocking out and it cost £120 so hardly expensive. They can be submitted to building control for approval.
But as you said if its just a rough idea you are after at the moment someone on here has probably done something similar.
Technially* I will need a building warrant ( Scotland ), so yes, it'd need someone properly qualified to do the actual submission. I'm just looking for rough figures at the moment to see whether I would need a beam height that would exceed the space I have. I am limited on the height of the opening due to the car I want to get in and out. I cant lift the roof, nor dig down the floor.
If someone came along along and said, this is how you calculate the weight of slate roof. This is how you modify its loading on the beam based on roof pitch etc etc that would be great.
*there is an existing wooden single lintel beam on the inside wall covering the whole span at the moment, and 3 separate stone lintels on the outer wall for each of the openings. The wood must be very old and rotting as other areas of wood like that have woodworm holes ... and the outer stone ones must be old and I'm terribly worried they would fail and it would so [b][i]repair[/i] [/b]of those existing lintels with a modern single span would be advantageous ..... 😛
Did something similar recently and supplied 2 No 203x133x30kg UB that were spaced so the outside of the beams were 350mm . These were then bolted together using M16 studding at 400 cars with round tube (scaffold tube size) spacers to keep the beams apart.
Cost to client was around £400 plus the dreaded.
That was for 4 metre beams (400 bearing each end with a 3.2m open span
My engineer head says there's plenty of space in there for a beam - but if you ask an actual structural engineer I'm sure they'd be able to confirm that before getting into actual calculations. 200x400mm will do you a pretty sturdy cross-section of steel!
Most beam suppliers will give you a guesstimate figure based on the info you have a above.
If clearance is that big an issue (although it doesn't sound like it will be), could the beam be situated on top of the existing wall? i.e. modify the trusses/roofline along the beam width to 'incorporate' it in to the roof?
could the beam be situated on top of the existing wall? i.e. modify the trusses/roofline along the beam width to 'incorporate' it in to the roof?
That would be something I'd want to avoid. The roof line comes down right onto the edge with no eaves ... Couldn't really lift it on its outer edge without it looking wrong.
[URL= http://img.photobucket.com/albums/v131/donboyfisher/House/Barn%20Outside_zpsla2vjnsc.jp g" target="_blank">
http://img.photobucket.com/albums/v131/donboyfisher/House/Barn%20Outside_zpsla2vjnsc.jp g"/> [/IMG][/URL]
Here are another couple of pics showing the inside beams . . . I'm not yet 100% what the beams come down and sit on. I need to chip away around one of the beams to see that. You can see the single long wooden lintel.
[URL= http://img.photobucket.com/albums/v131/donboyfisher/House/Barn%20Inside_zpst3fpwoju.jp g" target="_blank">
http://img.photobucket.com/albums/v131/donboyfisher/House/Barn%20Inside_zpst3fpwoju.jp g"/> [/IMG][/URL]
And here is a look at both the wooden inner lintel and you can see the stone lintel on the outside.
[URL= http://img.photobucket.com/albums/v131/donboyfisher/House/Barn%20Lintels_zps2ucn7hb0.jp g" target="_blank">
http://img.photobucket.com/albums/v131/donboyfisher/House/Barn%20Lintels_zps2ucn7hb0.jp g"/> [/IMG][/URL]
I had in mind to replace the outer beam such that it was what you saw from outside. no rendering/ masonry on it. Then have the doors hanging in line with the inside line of the opening. It doesn't need to be 100% waterproof or air proof ( in fact, the more air the door setup lets through the better for keeping the barn dry )
I think your barn's haunted, mate - middle pic, bottom left.
It would explain why my tools seem to go missing !