Screwing into the side of MDF or chipboard - loft door

[David.WE.Roberts]

I had decided to go with block board for the loft door because that is what the current (too small) door is made of and the blocks are good to screw into end on.

However block board seems about as common as rocking horse droppings - I understand that it is hard/impossible to get some that is FSC certified so the normal merchants are prevented from supplying by their own rules.

One alternative is to make a door out of insulation clad in timber and MDF but I am time and resource limited.

The big problem with other composite boards is the lack of strength if you screw into the end.

So I was wondering if there were any inserts - a bit like wall plugs perhaps - which could be sunk into the end of the board to provide a stronger fixing.

Any other strengthening options?

Gate style hinges bolted through could work, but might be a little less attractive to look at.

Cheers

Dave R

[Bob Minchin]

Drill a blind hole in from the back of the door to 80% depth perpendicular to where you want the screw hole and about 20mm in from the edge Insert a hardwood dowel and trim off flush. Drill a pilot hole for the screw into the edge of the mdf as far as the dowel. This will stop the mdf de-laminating. Insert a 30mm long screw so it passes through the centre of the dowel. If you have a number to do, making a jig from some scrap metal angle with holes in the correct places saves lot of marking out.

[Nightjar]

Metal angle screwed into the top face or U channel bolted through with tapped holes to take bolts holding the hinges?

Colin Bignell

[David.WE.Roberts]

Thanks - that sounds like a possible plan.

Still having perturbations about using MDF - rough aperture size is 1200 *

630 so it may be a bit large for a sheet to remain rigid at less than 25mm thickness which is pretty heavy.

I have read that blockboard is lighter that MDF and plywood so if I had to go to 25mm I might use some really old 25mm blockboard which I have in stock but this seems like overkill.

Blockboard is available on t'Internet at £40-£50 a sheet but delivery is about another £30 so this is pushing the price up a lot.

However £70 for a loft door may in fact be quite reasonable all things considered.

Cheers

Dave R

[David.WE.Roberts]

Thanks - another good though.

However please see my reply to Bob.

Cheers

David

[Bob Minchin]

MDF is crap really especially when considered on a strength to weight ratio. Depends on how much woodwork you want to do. A rail and stile panel door made from real wood and 5mm ply will be strong and light with some decorative features to give interest to a huge blank area. You could also make a torsion box construction with insulation inside. All depends on your workshop facilities and skill levels. Blockboard ain't that clever either. Sods law will put voids just where you want to put fixings and it is still heavy - to my mind 25mm is way too thick. Google for 'sagulator' to give an idea of the deflection of materials under their own weight.

[Harry Bloomfield]

David.WE.Roberts expressed precisely :

Could you not countersink the bolts holes on the face, fill and paint?

[The Natural Philosopher]

drill oversize holes. Fill with car body filler. When set drill with correct size holes.

[harryagain]

Make up a timber frame and secure the MDF to that. If you make the frame deep enough (ie boxlike) it can incorporate insulation too.

You can screw the hinges to the frame.

Or don't have hinges, just have it loose (pushing out upwards) and resting on beads Don't forget to incorporate draught strip.

[stuart noble]

Or use laminated pine board. It's only that and blockboard that will take a screw and be light enough to hold firm when it drops down by accident. The other solution is to make a wooden frame as the door out of 100 x

50, fill it with insulation, and hardboard back and front. Build a frame from the same material to take the door and fit the whole thing to the joists. Can't see a role for mdf at all really