Making internal doors

[stephenharris]

We're wanting to replace a few of the doors in our house, but I've found that for the shaker-style design we want, off-the-shelf doors will require more trimming than is allowed. We could go down the route of ordering bespoke doors but that doubles the cost.

It did get me wondering if it would be possible to make our own. I'm thinking either a frame the thickness of the door with 12mm ply/mdf panels recessed into it, or the sheet material is cut to the size of the door and the frame is glued and nailed on either side to make up the thickness (35mm / 44mm)

Is this a viable approach or will I end up with a warped door? Would dowels be sufficient for the frame? For the frame I was thinking hardwood, but would redwood also work? I'm limited on tools: I have a router, circular saw, and in particular no thicknesser/planer so I'm limited to dimensions I can get from the lumberyard.

Or is it an option to over trim the doors and reattach the lipping?

 

[Bingy man]

Hi there- I’m trying to understand your post regarding your concern with new doors as you say you would have to trim more than the allowed amount- so are the new doors a lot wider than the existing frames ? You then mention facing them with 12 mm plywood each side to make up the difference quoting 36/44 mm -but this measurement usually applies to the width of the door - 36 mm standard (ish) and 44mm are usually fire doors .pls clarify so the members can better advise you and add a few photos- removing the lipping and then cutting the door to size will require a lot of accuracy but it’s not impossible. Would a new standard frame + a new door be a better option in the long run. Reason I say this is I suspect we’re talking about an older property and if this is the case the frames are often twisted and not square etc ..

 

[Spectric]

Not all doors are made the same, some allow for more material to be removed than others and if buying then look for solid core doors and Deanta are sound.

You need to give us the door apperture sizes so we can better understand your concerns.

 

[deema]

Making doors by frame then gluing on MDF panels works very well. You’re basically creating a torsion box which is very stable and string. You can simply glue the frame parts to the panels, you don’t even need to fasten the frame together. So, dowels will work fine and add considerable strength (depending on size of dowel).
I would use Redwood rather than a hardwood, in fact I would go to the local shed and select the straightest white wood I could find rather than Redwood. The torsion box will help to stop any warping, but buy straightest stuff you can find. Planed all around (PAR) just means that, it’s planed, it doesn’t mean it’s actually straight.

I have in the past just cut the frame parts to size, and with yellow, white or cascamite glue just attached them to the panel. Lots of weight on top to apply pressure. However in your case, you could nail or screw the frame parts to the panels and then cover the nail / screw heads with the raised pieces to create the effect your after.

 

[ChaiLatte]

...I've found that for the shaker-style design we want, off-the-shelf doors will require more trimming than is allowed.

The trimming allowance given assures that enough of the part you trim remains so as not to affect the integrity of the door.

As said above, it is possible, but not easy, to slice out that part completely and replace it with your own timber recessed deeper into the door. If your time is worthless, that might be a cheaper option than trying to make a whole new door.

If you make the door from a central sheet panel and glue a frame either side of that (sandwich construction), it will make fitting the latch difficult. It would probably require the hinges to be routed. When you have a door stile that is homogoneous throughout, fitting the hardware is a lot easier. Hence, you might need at the very least to include a solid lock block in the appropriate place.

 

[Spectric]

but buy straightest stuff you can find. Planed all around (PAR) just means that, it’s planed, it doesn’t mean it’s actually straight.

or always square ! Any reason apart from cost in not using redwood ?

If you make the door from a central sheet panel and glue a frame either side of that (sandwich construction), it will make fitting the latch difficult.

Would it be any different to a modern cardboard door ?

 

[gregmcateer]

I know their service can be poor, but Howdens do make several sizes of their doors. If you can't see them online, visit a local branch

 

[Doug71]

How much you can trim off depends on the door, some of the cheap ones only allow 4mm per edge but some other ones allow 16mm per edge so might be worth checking a few different makes.

For example

https://www.oakwooddoors.co.uk/internal-door-solid-white-primed-coventry-4-panel-special-offer

The other option could be adding a couple of laths to the sides of a narrower door or packings on the casings/linings?

You can generally trim more off in height than is recommended if height is a problem.

 

[Diver Fred]

Firstley a couple links to Peter Millard on making your own out of MDF.




Trimming doors down to size; I have done it more than once, usually in the workshop but only once on site.

It's not simple to be accurate.

Me - if you can find doors you like that are solid wood then buy those!

 

[ChaiLatte]

Would it be any different to a modern cardboard door ?

I think he is proposing a slightly unusual form of construction. From his post "sheet material is cut to the size of the door and the frame is glued and nailed on either side", I think the sheet is the 'meat' and the frame is the (two slices of) 'bread'.

On a cardboard door, the hardboard sheets are the 'bread' (sourced from the same place as British Rail sandwiches) and the proper wood where the latch goes is a thick slice of 'meat'.

 

[deema]

@ChaiLatte I think you’re right, rereading his first post. That would be very unusual, and I don’t think it would work.

@Spectric I have suggested white wood as the construction I proposed means that it’s just there to separate the sheet material. He will I think find it easier to root through a pile of white wood at say B&Q than trying to find a wood yard happy for him to select out from redwood mixed grade.

 

[stephenharris]

so are the new doors a lot wider than the existing frames ?

No, the width is almost dead on (711mm, existing doors are just under that). It's trimming off the height that's the problem. Standard size is 1981mm, but existing door is 1948mm, which is 33mm. There are doors that allow up to 80mm to be trimmed off either side, but I've yet to find a panelled door that allows that much to be trimmed. Most seem to be at most 24mm. Some as little as 4mm.

I've attached a diagram of what I was thinking (though my sketchup skills don't extend as far drawing dowels). Actual dimensions will vary as I'm limited to off-the-self sizes (e.g. 95mm rather than 100mm).

Making doors by frame then gluing on MDF panels works very well. You’re basically creating a torsion box which is very stable and string. You can simply glue the frame parts to the panels, you don’t even need to fasten the frame together. So, dowels will work fine and add considerable strength (depending on size of dowel).
I would use Redwood rather than a hardwood, in fact I would go to the local shed and select the straightest white wood I could find rather than Redwood. The torsion box will help to stop any warping, but buy straightest stuff you can find. Planed all around (PAR) just means that, it’s planed, it doesn’t mean it’s actually straight.

I have in the past just cut the frame parts to size, and with yellow, white or cascamite glue just attached them to the panel. Lots of weight on top to apply pressure. However in your case, you could nail or screw the frame parts to the panels and then cover the nail / screw heads with the raised pieces to create the effect your after.

Thanks @deema - why Redwood rather than hardwood

You need to give us the door apperture sizes so we can better understand your concerns.

Aperture size is 1954mm x 715mm. With a 3mm gap all round that means a 33mm trim off the height. The existing door is 44mm but I don't need it to be a firedoor, and I can move the stops if needs be

If you make the door from a central sheet panel and glue a frame either side of that (sandwich construction), it will make fitting the latch difficult.

Yeah, good point. I was favouring the other approach anyway.

For example

https://www.oakwooddoors.co.uk/internal-door-solid-white-primed-coventry-4-panel-special-offer

That would be ideal, but they don't to 28" doors


So I think I will keep looking to see if there's anything off-the-shelf, but it's good to know that the dowelled frame around the panels would work. If it all goes wrong I can just fork out for the bespoke-builds and chalk this up as an expensive hobby

 

[Doug71]

Check out the sizes here, available in 711 x 1981

Like I said you are generally okay taking more off in height than they recommend you just end up with chipboard at the bottom instead of a wooden lath (depending on the construction).

https://xljoinery.co.uk/product/shaker-4-panel-internal-white-primed-door/

 

[ChaiLatte]

As above, it is a great deal easier to overtrim the height of a door than the width of a door.

First, the trimmed edge is never visible, only to the spiders. Second, no part of the door hardware interfaces with the trimmed piece.

If you are lucky, trimming off what you need will completely remove the manufacturer-provided wood there. You just have to measure the gap, plane a piece to that thickness and glue it in. Within reason, you do not need to glue it in very square or very flush* - you can trim or plane the bottom (top) after the glue has dried, or leave the door 5mm overlength and cut through everything at the end to achieve final size.

As all the doors will be the same thickness, you could get your timber supplier to thickness a standard piece to the correct measurement, so you just have to cut pieces off it.

Less desirable is a thin sliver of original wood left after the trimming: then you have to dig it out before introducing your new piece.

It would be good to probe the new door with a drill bit to see how much wood is provided top and bottom. That would inform you on how to distribute the trimming (half top, half bottom, all top, nothing at the bottom, etc.).

* put a couple of screws projecting from the piece when you push it into the door. It is hard work to retrieve it if you push it in slightly too far.

 

[toolsntat]

The key question in this situation is if the 33mm is trimmed in one go would you be ok with the bottom rail being so much narrower? I would notice but the majority of visitors to your home will have no idea it has even been done.
Don't forget you can take a little extra from the top while you are doing the fitting as long as it's got enough batten inside
The need to have replacement timber strips for the bottom is voided by using the piece from the offcuts.
Superglue and activator is the go to for refitting with a couple of cross pieces glued on to aid fitting and limit insertion depth. Glue inside face/ends and put a chamfer on the batten edge to allow the glue to distribute onto the face of it.
Cheers, Andy

 

[Diver Fred]

You have been sent PM outlining the way I modify doors. Doing the top and bottom is much easier than the sides. You may find that taking 33mm off the bottom you will clear the edge reinforcing batten.

 

[Doug71]

Might be wrong but I would guess that the doors I linked to would have solid MDF (or chipboard) stiles and rails so there wouldn't be any void to fill after they have been trimmed.