Door frame gaps plus jamb & head rebate sizes etc.

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Established Member
22 Nov 2019
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Market Harborough
Good afternoon. As part of a stable conversion I'm making a couple of exterior stable doors and frames from some lovely well-seasoned walnut which I've recently bought. I'm just working things out prior to making a cutting list and have a few questions for you experienced contributors if that's okay.
I'm starting with 125 x 125 mm laminated (from 2 pieces) posts for the jambs. The heads will be 125mm x 45mm.
1) I'm allowing for 2mm gaps between door and frame. Would this be enough for a weatherproof seal or should it be increased to 3mm?
2) I'm wondering how deep to cut the rebates into the frames. I've read various sizes between 10mm and 25mm and thought I might go for 19mm (3/4"). Would that work?
3) Instead of cutting a rebate, there's enough 19mm x 57mm timber to glue on stop beads after the doors have been fitted. Would that be a better option or should I stick with rebsates?
Thankyou for your help.
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I'll go through stuff as I see it. The jambs seem very large at 5 inch square . Walnut whilst an amazing wood isn't suitable for exteriors as far as I know(and expensive). Most joiners would put a rebate in the jamb/head 13mm(1/2inch) or so by the thickness of the door. Aquamac21 set in a groove doesn't need much clearance tbh. I'm not sure about what you mean by mitres sorry. Here's a pic of a spare I made.


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I just finished making a new frame and door for my garage. I made the door oversized and then could plane it down to fit. I'd make it as tight as poss to start with as it may shrink a bit as it dries out more.

I didn't cut a rebate in the frame as I wasn't sure what weather stripping I was using so a separate strip could be moved to accomodate different types/sizes.
Thanks very much for your reply Johnnyb. Sorry I mistakenly put 'mitre' instead of 'rebate' in my last sentence, (I was thinking that stop beads would be mitred). I've just edited my post to change that. I went with walnut because I'd read that, while not being the best timber for resisting insect attack (I was planning to treat it anyway), it does have natural anti-rot properties which I thought might be valuable. Apparently it's used quite frequently for outdoor furniture too, so that was another point which I thought to be in its favour. The pieces I have for the jambs, which apparently came out of a restaurant lobby, just happened to be 5" square and, since the doors will be a metre wide and pretty heavy, I decided to use them as they are. They could be cut down to 4 x 4 though, since they will be sitting behind the outer brick course.. The rebate size you suggested will be most useful. Suggested sizes from online reading do vary considerably. I must confess that you've set me thinking about the walnut though. :unsure: I like the finished effect of European oak, which would be the alternative, but I don't like the way it moves while you're working it. Thanks again.
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Thanks for your input Agent Zed. I've always used plant on stop beads on internal doors but this is my first foray into the world of exterior ones so I'm taking baby steps at present. Hence the need for advice.
It's strange to consider but say you make your frame 5 inch/side then the door stiles 4 inch/ side that's 18 inch of long grain to expand and contract causing issues. The frame needs to be rigid but gains strength from fixing to the wall. I'm presuming a machined in rebate would be much stronger over a plant on stop. Here's a simple door frame for plant on stops. Rebated frame would need uneven shoulders(to fill the rebate gap say 1/2 inch)


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Couple of thoughts, how big is the structural opening width?
I'm starting with 125 x 125 mm laminated
Am I right that your frame Jambs will be 125mm square, that is a lot of timber, and takes up a lot of the door opening width.

How thick will the door/s be? (I make mine @ 57mm) if you make the perimeter margin too small it will need a bigger leading edge chamfer applied to clear the jamb edge, which could then compromise the rebate depth on the closing face, and you would probably end up with the hinges binding as well.

I set my margins at least 3mm to 4mm all round on doors and generally use an 18mm rebate, I also use a double weather seal arrangement, 1 on the side of the rebate and one on the closing face of the rebate.

If your making a door for a "Stable" ignore everything I've said!
Thanks for your input Agent Zed. I've always used plant on stop beads on internal doors but this is my first foray into the world of exterior ones so I'm taking baby steps at present. Hence the need for advice.
Just to add that doing it the way I've done it does have some disadvantages too. Obviously you'll now have a join where water can potentially get in over time.

I should also say that in my case my door is opening outwards so you don't see the stop beads from the outside.

An advantage of stop beads though, may be that they rot first and can be replaced. rather than having to replace the entire frame or cut a piece and replace.

I personally think either way is fine.

I 'think' from the picture this one has separate beads for example
Thanks to everyone for your contributions. The doors are to be for domestic use and will be inward opening but, since the project is a stable conversion, I want to make them stable door type. I was going to try and make use of the existing stiles that came as part of the package I've bought, which will make the door width 977mm (door thickness is 45mm). As it happens the two door openings I'll be working on are actually different sizes but the one I'm concentrating on for this discussion is the wider one because filling in all that space is more problematic. On this door the opening itself is 1215mm (min) on the outer brick course but this widens to 1330mm across the inner course/reveal. I was planning to set the frame back behind the outer course within the reveal. Without increasing the length of the stiles the whole width of door + jambs (x2) plus 2mm gaps (x2) is 1233mm so, leaving the jambs at 125mm, there would still only be a 8mm lip behind the brickwork on either side. That's why I was concerned about the depth of the rebate. I take the point that it does seem a lot of space to be taken up by door jambs though, so I may have to increase the width of the doors in order to reduce the jamb sizes. It will be a fun project, once I've managed to get my head round it. The plan is to try and end up with something that looks like the door in the photo. I'll let you know how I get on.


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With those dimensions I would consider making a frame with a side panel or even 2, to get a sensible width of door, I would be a bit concerned that a stable door at that width will certainly drop.
I would do exactly the same just to try and bring the door back to reasonable proportions. Stable doors can be a pain.
I get that yes, but this one (on left) has similar proportions (1.2m wide & 2.2m high). I think we can probably live with that. Not so keen on the side panel to be honest. Thanks again.


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2mm could work for the gaps, but 3mm might offer better weatherproofing. 19mm for the rebates sounds solid, balancing fit and strength. Using timber for stop beads post-installation could be a neat touch.
That first door will be a mess after 2 winters. It's spindle moulded door using specific tooling that results in a door that looks like a composite door. In walnut I don't think it will hold up to good. Door making/fitting skills need to be up to scratch to stop any sagging. That panel may be insulated sandwich as well.
Victorians were so obsessed with proportion they wouldn't entertain a door so wide. The invented a style that gave the illusion of 2 doors but opened as a single door.(marginal stile door)
Thanks for the additional comments. Interestingly, it's a Victorian door, which is 4ft wide, which I'm replacing. The door pictured was apparently made by 'Timber Windows of Horsham' for a couple called Mr & Mrs Venn, of Pulborough. I'm not really here to agree or disagree with the timber-type, since I just picked the picture off Google to give an idea of the proportions (1.2m x 2.2m) as a follow up to yours and Johnnyb's concerns about those. Their brochure says it's Meranti, stained with a light oak stain. Admittedly it's 'engineered timber' but that's their claim anyway. Personally I'm not going to challenge them on it because, as already mentioned, I'm just interested in the proportions which seem to look okay to me. Here's their case study page though, if you wanted to check it out with them. I'm hoping my cabinet making skills will be sufficiently up to the challenge to prevent any sagging but will let you know how I get on. Thanks again.

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