90 degree joint for lean-to roof joist

[XTiffy]

The caps came without nails or screws. I chose to use green outdoor screws which are available in various lengths. The caps are in two parts held together with a small plastic extrusion (so caps do not get lost,) this is helpful as sometimes in the summer the cap can pop up with expansion.
I used a regular HSS drill but that idea of a masonary bit must have been meant for concrete sheets, for plastic sheets the wood bits would be ok.

 

[Chris152]

The caps came without nails or screws. I chose to use green outdoor screws which are available in various lengths. The caps are in two parts held together with a small plastic extrusion (so caps do not get lost,) this is helpful as sometimes in the summer the cap can pop up with expansion.
I used a regular HSS drill but that idea of a masonary bit must have been meant for concrete sheets, for plastic sheets the wood bits would be ok.

OK, that's great - thank you!

 

[XTiffy]

Chris 152,
I can't emphasize enough not to wind screws in too far, with plastic or unduline sheets it is easy to flatten or spread the sheet which messes up the meshing of adjacent sheets. As the screws go in at the crest, rain immediately flows down into the valleys, so a small"pinch" is all you need.

 

[Fergie 307]

I use these from seller eighty-twenty on e bay. They take size 8/10 screws. I much prefer using screws rather than nails especially on the clear sheets, they are quite brittle.

 

[trvlr]

Onduline have excellent tutorials re' fixing all manner of roofing materials; as does Aerialplastics.

https://www.ondulineshop.com

https://www.arielplastics.com

And there are excellent youtube vidoes re' the assorted systems; especially corrugated bitumen (some have been referenced by others on this forum).

If in doubt... no harm to add an additional support running the length/width(?) of the area to be covered by whichever material? Would help reduce any tendancy for sagging regardless of pitch of roof.

Width of roof for me (in the above offerng) is the measurement from one end to the other; length is the measurement from apex to guttering (if present).

 

[Fergie 307]

Main thing is to always start from the end of the roof furthest away from the prevailing wind direction, and work towards it. That way the wind will blow over your joints rather than into them. And stick to whatever recommendations the manufacturer has about overlaps.

 

[Chris152]

Done! All seems to have gone fine, we'll move the benches in tomorrow. We tested with a hosepipe, all seems good. Should be great for messy work. Thanks for your help all, really appreciate it.

ps At some point I'll get around to cleaning and painting that render...

 

[Chris152]

Quick update, just coz. The lad's attaching a 150 x 75cm 6mm plate to a 2'x3' surface plate we just picked up (for just £90, including the trolley) to use as a stick welding table, mig when conditions allow. The bench on the left was in the poly tunnel, made for lightweight stuff (and a bit long) so needed reinforcing to handle the vice. Bottom left are the cans I was asking about the CoSHH cabinet for, the petrol etc is now elsewhere. It'll make a great outdoor work space, really happy with it! (Tho the herbs to the right are looking a bit anxious.)

 

[MikeJhn]

Looks like the front and rear beams are relying on screw connections into the vertical supports/wall, not a good idea to rely on the shear value of the screws, may last a year or so, but eventually will fail, the new posts should have been under the beams, too late now, but letting a corbel into the posts will help as suggested earlier.

 

[duke]

Quick update, just coz. The lad's attaching a 150 x 75cm 6mm plate to a 2'x3' surface plate we just picked up (for just £90, including the trolley) to use as a stick welding table, mig when conditions allow. The bench on the left was in the poly tunnel, made for lightweight stuff (and a bit long) so needed reinforcing to handle the vice. Bottom left are the cans I was asking about the CoSHH cabinet for, the petrol etc is now elsewhere. It'll make a great outdoor work space, really happy with it! (Tho the herbs to the right are looking a bit anxious.)

View attachment 192517

Just curious what is the white vent cover over the window for?

 

[Jake]

Looks like the front and rear beams are relying on screw connections into the vertical supports/wall, not a good idea to rely on the shear value of the screws, may last a year or so, but eventually will fail, the new posts should have been under the beams, too late now, but letting a corbel into the posts will help as suggested earlier.

Or just screw/nail some 2 x 2 to the face of the upright under the beam so its bottom edge is supported by the end of the 2x2. Not as elegant but a lot quicker.

 

[Chris152]

Just curious what is the white vent cover over the window for?

There used be be an extractor fan there, the bricks on the outside weren't replaced so I put a vent cover over the gap - so it does nothing really.
eta - and the flower pot in the wall, top left, is to stop birds nesting in the vent from the utility room (never used, but required for building standards). One day I'll get round to putting a cover on that, too!

Looks like the front and rear beams are relying on screw connections into the vertical supports/wall, not a good idea to rely on the shear value of the screws, may last a year or so, but eventually will fail, the new posts should have been under the beams, too late now, but letting a corbel into the posts will help as suggested earlier.

I have coach bolts here that I was planning to put in, but will look at a corbel solution as you suggest - it'll probably end up closer to what Jake suggests tho! The screws into the wall are DeWalt Framid-Pro, about 40cm spacing, I've used them before and they're very strong.
To the right is a pergola I built several years ago using screws and coach bolts (and the same DeWalt fasteners to the wall), it's held up well, even with a full-size basketball backboard (and much pounding) since before Covid - I'd thought bolts would be adequate for such a light roof?

Very happy to take advice, though.

 

[MikeJhn]

Or just screw/nail some 2 x 2 to the face of the upright under the beam so its bottom edge is supported by the end of the 2x2. Not as elegant but a lot quicker.

And then relying on the shear value of the screw/nails.

Putting the coach bolt in is a good idea, but would have been avoided if built correctly in the first place and used compression type joints, i.e. the beams on top of the posts, I could go on about the undersize joists and the lack of noggins, I'm out.

 

[Chris152]

And there I was feeling quite happy with our new roof.

 

[Jake]

And then relying on the shear value of the screw/nails.

With the amount you could then get in all the way down that post, that concern is entirely theoretical. It's holding up a few sticks, some flimsy plastic and maybe a bit of snow as and when we see any, not a multi-story building.

 

[Jake]

And there I was feeling quite happy with our new roof.

As you say it looks like a useful outdoor work space.

 

[duke]

With the ledger board attached to the exterior wall firmly the friction created does add to the overall strength. As mentioned add additional support under the front beam on the post , every bit helps. Nice to have a dry area to work under!

 

[Fergie 307]

And there I was feeling quite happy with our new roof.

As you should.
As Jake says it's not some skyscraper.
Fair enough for anyone to point out ways in which it might have been done better, but to suggest it won't last a year is nonsense.
Enjoy.

 

[Fergie 307]

There used be be an extractor fan there, the bricks on the outside weren't replaced so I put a vent cover over the gap - so it does nothing really.
eta - and the flower pot in the wall, top left, is to stop birds nesting in the vent from the utility room (never used, but required for building standards). One day I'll get round to putting a cover on that, too!


I have coach bolts here that I was planning to put in, but will look at a corbel solution as you suggest - it'll probably end up closer to what Jake suggests tho! The screws into the wall are DeWalt Framid-Pro, about 40cm spacing, I've used them before and they're very strong.
To the right is a pergola I built several years ago using screws and coach bolts (and the same DeWalt fasteners to the wall), it's held up well, even with a full-size basketball backboard (and much pounding) since before Covid - I'd thought bolts would be adequate for such a light roof?

Very happy to take advice, though.

Spax wafer head screws are great for these sort of jobs, Screwfix etc.

 

[Chris152]

Spax wafer head screws are great for these sort of jobs, Screwfix etc.

Thanks Fergie - I'll bear those in mind for the rebuild next year.

I'll definitely beef up the supports, and maybe insert a few more joists (there is space to double them up). Time will tell...