Oak framed porch project

[lol22]

Hi all

I'm new to this site so please forgive any newbie gaffs and point me in the right direction? Thanks

My project is to build an oak framed porch. I have limited power tools and only very basic carpentry experience.
The basic idea is that the wall are constructed so that the frame is exposed inside and out with the spaces filled by obscured glass panels and a door (of course). The frame will look something like studding (1 metre centres but without the noggins). A single pitched roof with slate or shingles finishes it off. The roof overhangs the door by about 50 cm. Overall dimensions - width 3m, depth 0.5 m and height - tall enough so my 6' friends don't bump their head on the overhang.

The existing porch sits on a concrete pad. I am in two minds as to whether to remove or reuse the pad. For keeping the pad - simplifies the build. For removing the pad - it blocks air bricks that ought to ventilate a cellar room that I will convert (in the fullness of time ).

Questions -
Could I use sawn new oak sleepers for the frame? will it move so much that the glass would be broken. I would not paint it or treat it.
What type of jointing should I use for fixing the upright sections to horizontal sections? For the corners (especially at ground level)?
What tools would I need to make a good job of the joints? I presume I need a router? If so, what make - how much £ should I spend
Any suggestions for fixing the glass into the frame? I plan to rout a rebate and use some flexible fixing compound. But is there anything better? Is routing that much oak practical/ would be about 25metres to rout. Could I ask the wood yard to rout it for me?
Would cedar shingles look good with oak frame? Or is there something else to consider?

Thanks in advance

 

[zb1]

The glazing of the porch presents the biggest of your issues. Green (freshly sawn) oak if very easy to work and you don't need much in the way of a tool kit. My basic power kit is a C9U circular saw, good cutting depth, and a slow speed high torque drill, for augering out 40mm mortises. I also use a Mafell chain mortiser but this might be a bit pricey for making a single porch. You can do all the work with hand tools and sweat if you fancy it. Mortise and tenon joints account for 90% of framing with scarves, cogging and bridle joints making up the rest.

Back to your glazing issue. Green oak will shrink in the region of 10-12% across the grain as it dries but about 0.5% along its length. This needs to be accounted for when introducing glass and to a slightly lesser extent door frames. I use a direct glazing system where the glass if floated on to of the oak then cover boards are mounted to sandwich the glass to the oak allowing for movement. I would strongly advise against using a rebated system as they are more prone to leakage and damp ingress causing the oak to stain and mildew growth which turns the oak black.
Shrinkage is not the big issue though, knots and wind (not the blowing sort but the twisting sort) are. Timber selection is everything with glazed oak frames. It literally makes or breaks the system.
I would definitely not get green oak sleepers. You should really be using a experienced sawmill that can grade the timbers to a glazing or QPA (French quality grade)/THA or TH1(Brithish grading).

Roof covering wise it's less what it looks like with the oak, more whether it is sympathetic/complimentary to the existing building. Shingles on a brick and clay tile building won't look that great in most cases. With stone and/or thatch it'll be better.

There is no need the paint or treat the oak. Some people like to have an oiled finish but when exposed to UV light it will still go grey in the long term.

Any ways if you have any more questions feel free to PM me or click on my signature.

Zach ( Sheffield based timber frame and timber engineering specialist carpenter)

 

[lol22]

zb1

Thanks for your thoughts. It is clearly more complicated than I hoped. I will have to improve my jointing skills.
I hear your message about having the right grade timber. I found a supplier on line and may look closer to home also.

btw - I need to be on this site longer to use PM
Mods - hope this next bit isn't inappropriate, zb1, I am not far from Sheffield and would be interested in your thoughts as to how much it would cost to have something like the porch I am describing built for me.

 

[zb1]

The framing bit isn't all that complicated, it's more the framing to glaze that complicates matters. If you were just going for an open sided porch I'd say go for it. It's hard graft but I love it and it's pretty easy to pick up. But if you want a closed porch with glass and a door then things get trickier, less room for even very small errors and possibly a bit of a mess in the end (not passing any sort of judgement on your carpentry skills), especially where weather, oak and glass are concerned. I could regale you all with horror stories of glazing and green oak gone wrong but I don't want to put people off, after all I do make a living out of framing. Suffice to say, if it's done correctly there should be no problems further down the line.
If you want to have a go I would recommend getting a copy of Rupert Newman's book Oak Frame Buildings. A very good introduction to the basics of designing and building with green oak. Another popular one is Ted Benson's Building the Timber Frame House, a much more in depth look at framing US style (not the way we do it over here and obviously not as good as our way ) but still a good reference.

Zach

 

[Togalosh]

I hope you don't mind me butting in with a question too please?

I am also looking to build a glazed, green oak porch & now I'm so glad I've not rushed into it as by what you've said Zach it would've gone horribly wrong by now !

I thought I knew more or less how it will be done but now I'm not sure.. so I have that book you recommended in my shopping basket ready to go but I just want to know if it will show diagrams of various glazing options or the glazing option you recommended ? It's only a tiny porch compared to your work (which looks ace btw) that would be 1/2 wood, 1/2 glass.

Thanks
Steve

 

[zb1]

Steve, I haven't got my copy to had as I have lent it to someone. Rupert's book does cover glazing briefly and has 2 or 3 diagrams of the glazing system I think. It's less of a how to book and more of a description of the whole design, manufacture, erection and finishing of framing. There are other more DIY/learning book available but they are mostly USA based timber frame books with different styles of manufacture and design. TRADA do a book called Green Oak in Construction which is much more technical but costs £65.
Glazing to green oak is a tricky one. I don't want to put people off but it is mostly about experience. having the right kit and good quality materials (just like most woodwork really). It is very labour intensive and can be quite fiddly to get it looking just right and functioning well. As a guide the glazing costs can account for as much half the total on jobs like sun rooms and large 2 storey glazed gables. I reckon on some jobs I've spent longer planing, thicknessing and machining the boards than I have cutting the frame and most glazed jobs are longer on site glazing than erecting the frame.
My worry is that I might be sounding a bit "ooh are you sure you've got the skills" and being a bit high and mighty but I really don't want anyone going out and spending several £100s or £1000s only to end up with a product that they are not happy with after a pineapple load of time. As I said earlier most of it is just experience. If you feel confident go for it, if not consult with a specialist firm and get some ideas of cost. It will be a permanent addition to your property so don't rush in all guns blazing.

Hope that wasn't too disparaging.

Zach

 

[Togalosh]

Zach,

I take all advice, arguing & criticism as intended as I believe all on here are here to help ,so I am more than grateful for all your thoughts.

It's a tiny porch & I can get a van stuffed full of "left over" oak for £80 in all sizes ..it's 1/2 dried but badly dried but I love it (knots & all).. even if it takes me a long time to sort, machine & rough out. I cannot afford kiln dried stuff & besides the local suppliers are a bunch of teeth sucking, toss pots who are very dismissive if you don't talk the patter to them. So cost is not a big issue & my confidence is growing by the day, I am conscientious worker & I think my design skills are better still ..so it'll look good (from a distance at least !) but I hate failing & also it's the time I've not much of so a lot of reading & sketching is done before I pick up tools.

Thanks again.