More questions about a cut roof
- Thread starter garyo
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Couple of things first.
Your first common on back wall will sit on the end or your ridge plate
Should read.
Your first common on back wall will sit on the end {of } your ridge plate.
Google www.kingsviewoptical.com/Roofmaster The diagrams may help you understand what I will be talking about.
Also forgot to say, where wall plates meet with one another, half lap them together, same on corners.
Pleased to see Noseall has run his eagle eye over it, he only does it to call me Old Codger. At least with him riding shot gun, you will now buy one, get one free.
As Nose says 400or600mm centres are your choice. You will save on your rafters, but loose out if you are using 12.5 plasterboard as you will have centre noggins to put in for plasterboard. We go 600 c/ unless we are on plain tiles or slates then we go 400 c/ to stop bounce on battens.
You now have one rafter up on return against existing house and rafters at what ever c/ you decided on, up to dog leg. Fit ridge plate on short return, line up top outside corner of short ridge plate with top of last rafter, level and fix.
IMO, would not do barge and soffit to gable, will look bit fussy, would do neat cut to facework, cloak and bed tiles. Your choice. Measure and finish last rafter. Move last rafter to inside of gable wall so that ceiling joist will pick up plasterboard.
Your hip rafter needs to be third as long again as commons. Depending on span, if we are using 50x100mm commons we would make hip rafter 50x150. How ever if you already have bought a 50x100, don’t worry, it will be strong enough. If your roof is say 30degree pitch, as said previously your plumb cuts will be 60 and seat cut 30, but your hip plumb cut will be 68 and seat will be 22 degree. Don’t worry about all this malarky though, as I am telling yer the way stonehenge was built, bits of string and astronomy.
As Nose said before you go any further, square your plate corner of where hip rafter will sit, look in the site I told you to google page 16 and it will give you a picture. When you have done that and assuming you are using 50x100 as hip, set yer bevel to say 68 degree, crown yer hip, mark the top and run skill saw through. place up on ridge plate and use same 110mm block on bottom with block plumbed up from the diagonal that you have cut of corner of wall plate. As you did for commons. Push hip tight to wall. Make sure it is centre of two crown rafters and centre of block on corner of wall plate. Put short length of 25x50 on side of rafter that is against house and scribe line up the 25mm edge, This is yer plumb cut. While yer there, run yer pencil under the hip down the sides of the two crowns. this gives yer your mitres, but if everything is right they should be 45 degrees, don’t worry about your bottom plumb line yet.
Square your top line all round hip.
Going to call it a day now. Got lot on plate at moment, but will try to clear you up by Friday, hopefully Nose will read this through and see something I have missed to date.
old un.
Your first common on back wall will sit on the end or your ridge plate
Should read.
Your first common on back wall will sit on the end {of } your ridge plate.
Google www.kingsviewoptical.com/Roofmaster The diagrams may help you understand what I will be talking about.
Also forgot to say, where wall plates meet with one another, half lap them together, same on corners.
Pleased to see Noseall has run his eagle eye over it, he only does it to call me Old Codger. At least with him riding shot gun, you will now buy one, get one free.
As Nose says 400or600mm centres are your choice. You will save on your rafters, but loose out if you are using 12.5 plasterboard as you will have centre noggins to put in for plasterboard. We go 600 c/ unless we are on plain tiles or slates then we go 400 c/ to stop bounce on battens.
You now have one rafter up on return against existing house and rafters at what ever c/ you decided on, up to dog leg. Fit ridge plate on short return, line up top outside corner of short ridge plate with top of last rafter, level and fix.
IMO, would not do barge and soffit to gable, will look bit fussy, would do neat cut to facework, cloak and bed tiles. Your choice. Measure and finish last rafter. Move last rafter to inside of gable wall so that ceiling joist will pick up plasterboard.
Your hip rafter needs to be third as long again as commons. Depending on span, if we are using 50x100mm commons we would make hip rafter 50x150. How ever if you already have bought a 50x100, don’t worry, it will be strong enough. If your roof is say 30degree pitch, as said previously your plumb cuts will be 60 and seat cut 30, but your hip plumb cut will be 68 and seat will be 22 degree. Don’t worry about all this malarky though, as I am telling yer the way stonehenge was built, bits of string and astronomy.
As Nose said before you go any further, square your plate corner of where hip rafter will sit, look in the site I told you to google page 16 and it will give you a picture. When you have done that and assuming you are using 50x100 as hip, set yer bevel to say 68 degree, crown yer hip, mark the top and run skill saw through. place up on ridge plate and use same 110mm block on bottom with block plumbed up from the diagonal that you have cut of corner of wall plate. As you did for commons. Push hip tight to wall. Make sure it is centre of two crown rafters and centre of block on corner of wall plate. Put short length of 25x50 on side of rafter that is against house and scribe line up the 25mm edge, This is yer plumb cut. While yer there, run yer pencil under the hip down the sides of the two crowns. this gives yer your mitres, but if everything is right they should be 45 degrees, don’t worry about your bottom plumb line yet.
Square your top line all round hip.
Going to call it a day now. Got lot on plate at moment, but will try to clear you up by Friday, hopefully Nose will read this through and see something I have missed to date.
old un.
The only thing wrong with using a hip rafter the same depth as the rafters (jacks or commons) is, it will not be deep enough to collect the whole of the plumb cut.
Granted, the shallower the pitch the less of the plumb cut will be showing, but i do not like to see any of the plumb cut showing whether it be on a ridge board or a hip rafter.
The same thing happens when you run a ring purlin around a hip roof where the purlins join on the hip rafters. There is usually 3 or 4 inches of the purlin mitre cut dangling below the hip blade. we always fix additional timber beneath the hippie to collect the whole of the purlin cut.
Thanks again both.
When you suggest not bothering with the soffit/fascia on the small gable end, I like the sound of that.
Can you explain the detail of that - My guess is that I'd do the follwing:
* build the inner and outer leaves up to top of rafter level
* then finish my battens and undercloak half way through the outer leaf?
* bed the tiles down on mortar on the outer leaf and make sure the tiles have a 5 cm drip overhang?
Would I then finish my wall plates so that they sit on the inner leaf at that end, and only the battens extend over half of the outer leaf?
I can't quite picture how I neatly close off the end of the eaves. I'm sure it'll come to me though!
Gary
When you suggest not bothering with the soffit/fascia on the small gable end, I like the sound of that.
Can you explain the detail of that - My guess is that I'd do the follwing:
* build the inner and outer leaves up to top of rafter level
* then finish my battens and undercloak half way through the outer leaf?
* bed the tiles down on mortar on the outer leaf and make sure the tiles have a 5 cm drip overhang?
Would I then finish my wall plates so that they sit on the inner leaf at that end, and only the battens extend over half of the outer leaf?
I can't quite picture how I neatly close off the end of the eaves. I'm sure it'll come to me though!
Gary
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A cut-brick gable as opposed to a barge gable with soffit box requires either a concrete corbel or a brick corbel to deal with the soffit end.
Gary, Just deal with what Nose has said first. I know where he is coming from, but in your little roof it is neither here nor there. Yer 50x100mm hip is coming down at 22 degrees and a plumb line on that is 107mm long, yer plumb cut on yer 50x100 hip spars are 115mm long. I loose no sleep over yer spar hanging down 8mm below hip. I would loose no sleep even if it was hanging down 30mm, as long as it fitted snug and was well fixed. So scrub that one.
Back to gable, yer nearly there but not quite cut yer wall plate of back of blockwork. Don’t matter about building over top of plate. take block work up to 15mm down below rafter. Face work, if yer doing cuts with lump and bolster, keep cut down 10mm below rafter. Am getting in front of me self telling yer this now, so will come back once roof is finished, and well tell you how to finish facia with out corbels.
I was up to top plumb cut last time.
Put short length of 25x50 on side of rafter that is against house and scribe line up the 25mm edge, This is yer plumb cut.
Forget that way, do it this way, be easier. Block 50x100 say 300mm long, place against house wall outside of hip, slide over to hip and scribe plumb line down. Down to bottom, plumb, and scribe line up from the triangular piece you have cut of. Should be same degree as top.
Go back to top cut, square it all round, now your two cuts underneath should be 45 degrees, if they are not, then something is not square. Not to worry, set yer bevel to underneath line, turn er over, and put bevel on top and scribe line, do same to other one and you will have point, arrow call it what you like on top. Go to web site page 12 and 18 will show you what I mean.
Set blade on skill saw to 45 degree or what ever required to cheek cuts. Suggest you make up bevel to run your skill saw down, as if you have a skill saw bought in this country, its a pigs ear to see your line over the saw. We buy our Dewalt battery skill saws from The States, blade is on left, find it easier to see line. If your skill saw only cuts 45mm on angle finish with handsaw.
Down to bottom, measure HAP of common rafter, mark this measure down on hip rafter plumb line, square this across to give birdsmouth, Seat cut should be about 22 degrees. Cut out and see if she fits Tomorrow will tell yer how to drop hip if she needs it, and cut jacks.
Gary, hope you have been under standing what I have been talking about. Tried to explain in the same way the ancients used to work, pencil, bit of string bevel and level. If yer ain’t got level, bucket water and length clear plastic tubing.
old un. put a thanks ups so I know yer have read it.
Back to gable, yer nearly there but not quite cut yer wall plate of back of blockwork. Don’t matter about building over top of plate. take block work up to 15mm down below rafter. Face work, if yer doing cuts with lump and bolster, keep cut down 10mm below rafter. Am getting in front of me self telling yer this now, so will come back once roof is finished, and well tell you how to finish facia with out corbels.
I was up to top plumb cut last time.
Put short length of 25x50 on side of rafter that is against house and scribe line up the 25mm edge, This is yer plumb cut.
Forget that way, do it this way, be easier. Block 50x100 say 300mm long, place against house wall outside of hip, slide over to hip and scribe plumb line down. Down to bottom, plumb, and scribe line up from the triangular piece you have cut of. Should be same degree as top.
Go back to top cut, square it all round, now your two cuts underneath should be 45 degrees, if they are not, then something is not square. Not to worry, set yer bevel to underneath line, turn er over, and put bevel on top and scribe line, do same to other one and you will have point, arrow call it what you like on top. Go to web site page 12 and 18 will show you what I mean.
Set blade on skill saw to 45 degree or what ever required to cheek cuts. Suggest you make up bevel to run your skill saw down, as if you have a skill saw bought in this country, its a pigs ear to see your line over the saw. We buy our Dewalt battery skill saws from The States, blade is on left, find it easier to see line. If your skill saw only cuts 45mm on angle finish with handsaw.
Down to bottom, measure HAP of common rafter, mark this measure down on hip rafter plumb line, square this across to give birdsmouth, Seat cut should be about 22 degrees. Cut out and see if she fits Tomorrow will tell yer how to drop hip if she needs it, and cut jacks.
Gary, hope you have been under standing what I have been talking about. Tried to explain in the same way the ancients used to work, pencil, bit of string bevel and level. If yer ain’t got level, bucket water and length clear plastic tubing.
old un. put a thanks ups so I know yer have read it.
Thanks oldun, noseall.
The roof is progressing well, but today I had the building inspector in to check over the build up to wall plate level, as he'd not laid eyes on it since hardcore. Thumbs up apart from my box lintels aren't adequate due to them not being cavity lintels, so I'm going to have to swap those out for cavity/top-hat lintels, even through there'll be no weight on them on the outer leaf.
So, the roof will be delayed slightly now
The roof is progressing well, but today I had the building inspector in to check over the build up to wall plate level, as he'd not laid eyes on it since hardcore. Thumbs up apart from my box lintels aren't adequate due to them not being cavity lintels, so I'm going to have to swap those out for cavity/top-hat lintels, even through there'll be no weight on them on the outer leaf.
So, the roof will be delayed slightly now
You have yer hip cut make sure she fits. leave in place, get straight edge about 2.4m long and lay it over two or three commons above your birdsmouth and slide it to wards your hip rafter so that it cuts and touches the top corner edge of hip, it should be near enough, if a bit high will come back to that in minute.
Now try it up the top exactly the same. Top should be right. Now go back to bottom, if it is only 2to 3mm high, then don’t worry about it, will not show on tiling. If it is higher than 2to3mmm then measure what it is and reduce your seat cut by this amount. Use yer skill saw and template. If yer take a bit to much of don’t worry, run your skill saw down the side of bit of 50x100 and take a 2to3mm ripping of and use that as packer under birds mouth.
Going to leave that for a bit now, as have read about yer lintels and want to tell yer something before you put new ones on.
If you are using standard IG lintels and 9mm PVC soffit board then bed yer lintels up by 12mm on both outside and inside skin. Last thing at night when the bed under the lintels has well addled of, rake out 30mm deep the joint tween top of brickwork and lintel down the reveal and along the front of lintel. Reason, so that you can cut slot out of soffit and slide it in so that sits on brickwork and head of frame and lintel is enclosed and not seen. Think about it, draw small sketch, it will come to you. Be back tomorrow. Also would like you to explain to me how you did your drawings that you posted.
Old un.
Now try it up the top exactly the same. Top should be right. Now go back to bottom, if it is only 2to 3mm high, then don’t worry about it, will not show on tiling. If it is higher than 2to3mmm then measure what it is and reduce your seat cut by this amount. Use yer skill saw and template. If yer take a bit to much of don’t worry, run your skill saw down the side of bit of 50x100 and take a 2to3mm ripping of and use that as packer under birds mouth.
Going to leave that for a bit now, as have read about yer lintels and want to tell yer something before you put new ones on.
If you are using standard IG lintels and 9mm PVC soffit board then bed yer lintels up by 12mm on both outside and inside skin. Last thing at night when the bed under the lintels has well addled of, rake out 30mm deep the joint tween top of brickwork and lintel down the reveal and along the front of lintel. Reason, so that you can cut slot out of soffit and slide it in so that sits on brickwork and head of frame and lintel is enclosed and not seen. Think about it, draw small sketch, it will come to you. Be back tomorrow. Also would like you to explain to me how you did your drawings that you posted.
Old un.
Why?
We always use a box lintel above an upstairs window whereby it becomes an eaves detail as opposed to say a gable. As you say, all there will be above is fresh air. The box sits upon the inner leaf and the soffit board sits directly upon the outer leaf.
In some instances there is a single course of brickwork showing above the windows but this is not a typical scenario. In these cases a cavity lintel is essential.
The only thing i can think of is the window span is above 2m and the strength issues with a standard box will not comply. You could install a HD spec box if necessary?
Otherwise using a lintel with a lip or an outer carrier is not only pointless but it interferes with the soffit.
Do you have a course of bricks above the windows?
We agree with Nose 100%, he is right in all that he has said. However saying that we had a similar problem three years back and we lost three days arguing about it with BC. For some reason or other they don’ t like the Catnic Clasic Box eaves lintel, so now we always fit open back Catnic CGE 90/100 or IG L1/E 75 for 70/100. As both the above lintels usually have to be ordered, we just use standard open back. The only difference is a standard open back is 283mm wide and open back eacves is 248mm wide. Think I have remembered them right.
Whatever you use the most important bit is as I explained previous post. bed lintels up 12mm and rake out joint on face skin so that 9mm soffit will slip under lintel and sit on head of frame
If you do not understand what I have said, then say so and will explain in more detail.
Have some breathing space now, so will be back in 2/3 days.
Leave yer with a couple of words me old granddad said to me a lot of years ago. Best way to learn son is when it hits yer pocket.Flag it when when you havd read it.
old un.
The widest span is 105cm. There's no course of bricks above the windows on the outer leaf, it's all as per one of my earlier diagrams (see below)
Is it the thermal aspect of it - given that the steel box will conduct far more than a layer of thermalites used with a cavity lintel? I should have asked more questions, but wanted to appear to be compliant.
Strangely, he said he doesn't want to come to inspect first fix etc, so will come back next when the roof is finished and the place is plastered, therefore I'm tempted to leave the lintels as they are and then see if he forgets. The impression I get is that he thinks of it as a silly little porch, and he often asks me questions about what I'm doing that are obvious if he'd even glanced at my plans, so there doesn't seem to be much structure of formality to the inspections.
To make things more fuzzy, he had a look around and initially didn't have an issue with the lintels at all. It was only towards the end when I started discussing that I was going to widen the old front door into the existing house, and asking his advice on what kind of lintel I should use, that he wanted to find another lintel to refer to...i.e. he said "what you want to use for front door is a lintel a bit like, um, <looks around the place> <looks at new box lintels>, hey, what sort of lintels have you used there"
Gary
Hi OldUn,
For my plans I use Microsoft Visio. It produces scale drawings, but isn't a proper CAD package so does take quite a bit of work to get reasonable results from. e.g. if I decide to change a dimension on a plan view, then I also need to manually make the same change on every other projection/plan that includes that dimension.
Thanks for your help, and the same to Noseall, as always.
Cheers
Gary
For my plans I use Microsoft Visio. It produces scale drawings, but isn't a proper CAD package so does take quite a bit of work to get reasonable results from. e.g. if I decide to change a dimension on a plan view, then I also need to manually make the same change on every other projection/plan that includes that dimension.
Thanks for your help, and the same to Noseall, as always.
Cheers
Gary
I can not think of a single reason why a (two course) box lintel would not be satisfactory.
For example:
A 1050mm ST 100 box will carry 23.52KN.
It will not only deal with your roof.... it will EAT IT!
Gary, Lets sort this lintel problem out. If you fitted a 143x100mm standard box lintel, then these are not acceptable, as they have not got a toe to cover the gap between back edge of window and lintel, consequently you have nothing to float and set to, although we do not float and set reveals and heads now, we dot and dab them with a 10mm hang out of plasterboard over blockwork and float our walls to the plasterboard. Stick angle skim bead up and skim the lot. We do this, due to the fact of plaster cracking where it has gone over the thermobate cavity closures.
Since we have switched to open back lintels over eaves , we also like the fact that people find it easier for curtain fixings as they are fixing into blockwork instead of steel or a length of batten.
If you have put in standard143x100mm box lintels, and BC are not coming round until after plaster, then I would be inclined to leave them in and do the following to make them workable.
Cut bit 25x100 300mm longer than lintel, screw it on to back of blockwork level with bottom of lintel. Fit a 50x100 piece of timber to this and you have formed 75mm toe to lintel which will close gap between lintel and frame. If you are going to float and set, nail bit of metal lathe over timber, if dot and dab just go over the lot with dabs.
Forgot to say stuff lintels with fibreglass to get some Restance value.
Anything you do not understand, let me know, nothing to be ashamed of. One other thing , we set our windows back now 65mm into reveals to comply with NHBC. Door frames 40mm back, so that you can get fixing to facework. Windows we strap back to blockwork. Couple straps on door frame as well sometimes
old un.
Since we have switched to open back lintels over eaves , we also like the fact that people find it easier for curtain fixings as they are fixing into blockwork instead of steel or a length of batten.
If you have put in standard143x100mm box lintels, and BC are not coming round until after plaster, then I would be inclined to leave them in and do the following to make them workable.
Cut bit 25x100 300mm longer than lintel, screw it on to back of blockwork level with bottom of lintel. Fit a 50x100 piece of timber to this and you have formed 75mm toe to lintel which will close gap between lintel and frame. If you are going to float and set, nail bit of metal lathe over timber, if dot and dab just go over the lot with dabs.
Forgot to say stuff lintels with fibreglass to get some Restance value.
Anything you do not understand, let me know, nothing to be ashamed of. One other thing , we set our windows back now 65mm into reveals to comply with NHBC. Door frames 40mm back, so that you can get fixing to facework. Windows we strap back to blockwork. Couple straps on door frame as well sometimes
old un.
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