flat garage roof - how to make

[glerwill]

Hi,
I intend to replace the flat (it has a fall from front to rear) roof on the garage, which is currently wriggly tin supported by metal tubes (yes that good a leaking bodge job!) with a fairly standard timber roof.

There is already a 'lip' on the side of the house at the correct fall, that is not currently used.

The dimensions are 3.2m x 5m - ! would wish to span the joists accross the 3.2m and use timber attached to the house wall one one side and supported by the garage wall on the other side, along with metal joist hangers and 18 mm chipboard on top.

My questions are two:

What would be the best choice of joist dimensions and spacing - I would wish to minimise roof depth.....

What is the best way to waterproof the roof and join it to the 'lip' )sorry I dont know the right word) on the house, as a DIY job. I am looking to achieve a 15 year plus solution!

thanks graham

 

[noseall]

175mm x 50mm at 400mm c/c.

Use 18mm ply or even osb not chipboard.

The roofing membrane can either be channeled into a mortar joint on the upstand or use a lead cover flashing. The lead option offers a more flexible solution.

 

[glerwill]

thanks for the quick reply

Ive the garage door to do first then replace the roof after that

 

[glerwill]

Hi,
I'm ready to start the job now. The 47 x 175 joists and 18 mm WBP plywood are coming from a local timber merchant - bandq and wickes did not have the joist sizes -£389 incl vat/delivery.

I am intending to use the simpson strongtie timber joist hangers from wickes with the joists across the 3M span. To support these joists, I currently intend to bolt the same section timber as the joists to the existing walls - poured concrete twin leaf on one side and 100 mm block/brick on the other side.

Eventual waterproofing is intended to be an epdms rubber roof covering.

My questions are two:

- is this a reasonable way to do this?

- what size bolts and at what spacing to be structurally sound?

many thanks for your help

Graham

Hi,
I intend to replace the flat (it has a fall from front to rear) roof on the garage, which is currently wriggly tin supported by metal tubes (yes that good a leaking bodge job!) with a fairly standard timber roof.

There is already a 'lip' on the side of the house at the correct fall, that is not currently used.

The dimensions are 3.2m x 5m - ! would wish to span the joists accross the 3.2m and use timber attached to the house wall one one side and supported by the garage wall on the other side, along with metal joist hangers and 18 mm chipboard on top.

My questions are two:

What would be the best choice of joist dimensions and spacing - I would wish to minimise roof depth.....

What is the best way to waterproof the roof and join it to the 'lip' )sorry I dont know the right word) on the house, as a DIY job. I am looking to achieve a 15 year plus solution!

thanks graham

 

[glerwill]

So,
I took the lack of replies as 'crack on'. I will start tomorrow by marking out the speedy joists and attaching them to the timber 175 x 47 and attach to the wall with 135 x 10 frame fixings. I note that these are 'medium' weight rated so I am going to use some 10 x 60 heavy duty rawlbolts just in case. So I am going for 2 heavy duty and 5 medium duty fixings on a 3m length to attach to the wall.

I'll let you know how it goes.

Any comments or suggestions welcome.

Graham