Exterior Plywood Doors

Doors. You don't often think of them - but they're essential.

For thousands of years we have constructed all forms of doors across all continents to be a barrier to the outside.

To provide a sense of security like a tent door flap to top grade all elements protection of a nuclear blast door.

This Instructable is the basics. A plywood door.

Plywood - 12mm in this example but 15mm or 18mm will be stronger and heavier

(If exterior grade you expenses will triple)

T Hinges - 300mm in this example - 2 per door but you can use standard hinges if preferred

Drill

Saw

Router with V bit

Square

Rule

Clamps...lots

Straight edge

Wood Glue - exterior

Epoxy resin 2 part glue

I need 2 doors. Nothing special. These are on the back of our garage to two separate small 'outhouses'. In the past few years I noticed woodworm had got in but at that time it just couldn't be delt with. Recently on inspection the problem was a lot worse - not only the doors, the door frames, the fascia above and the beam behind in the roof space.

Now getting someone in to do this would be too costly. Also why do that when I can do it myself. Initially I thought I could just buy doors in and fit but I just couldn't find any that suited or didn't require me to sell a kidney to afford them!

So I looked into building them following the initial construction of the original doors - a tongue & groove braced door. But as I started looking into the cost of exterior grade softwood the price was going in the wrong direction.

I then turned towards plywood - exterior marine ply was again built to do a job but too expensive. I figured if I could build out of standard ply sheet but if seal well then it should be up to the task.

I live in the UK. We have quite varied weather and we love to talk about it. But damp and wet conditions are a fact to deal with when contemplating construction of using wood outside.

The idea is to use plywood sheet to create the main panel of the door and then 'thicken' it up using more ply by 'sandwiching' it together.

As the ply is 12mm it will end up 24mm thick. It could be 3 layer (36mm) but I don't think its required and the weight factor increases.

My layout design was to try and get the maximum out of the panel with efficient cutting. It doesn't really matter on the width of the side/top/bottom panels - it just stiffens the door up. It also aids increasing the depth of the fixings to be placed. For example hinge screws.

I need 2 ply panels for 2 doors although there will be some left over for other projects.

So each door is:

• Main Panel 2180x765
• 2x side panels 2180x110
• 5x cross panels 540x112

Time to go to work. We had a few days of sun so this allowed for the outhouses to sit open.

The doors, framework, guttering and fascia board all got removed to discover the beam behind was infested as well. So all was removed. Now this Instructable is not about the frame and rebuild, but the basics will be shown here.

I tend to recycle and reuse a lot of wood - mostly from old door and window frames as this is usually a hard wood. Nails/screws/holes/rot/paint/silicon are the obstacles you have to deal with but I'm used to it.

So the frames were made from recycled hardwood approx. 40x50mm. These consisted of 2 uprights and a cross beam. I had an issue with bowing in the wood but it wouldn't be too much of an issue. These were primer painted and I used epoxy resin glue to seal the ends on the floor as well as setting them off the floor with 3mm plastic spacers. Aluminium tape was also used on the side touching the wall to decrease water penetration.

A new beam was put in (100x40) with a new fascia board (a gravel board was used 125x25). Sanded, primed and gloss painted. The guttering will be placed on this.

By constructing the frame and getting it placed I could be more accurate on the actual door size instead of cutting after.

The Plywood is 12x2440x1220mm

The safest way to cut the main door panel was laying the sheet down on battens, marking up and using a straight edge to cut using a circular saw.

NOTE: using masking tape for where the blade is cutting helps reduce wood tear out.

The main panel was 1980h x 765w. The first cut removes a panel that is then cut into strips 112mm wide for the cross panels. The second main cut is to remove the side and then cut to create the 4 long side panels 110mm wide.

In theory this is simple....right?

Spread glue on, place it, clamp it, done!

So initially I couldn't squeeze the glue out fast enough - ended up removing the top cap.

Used an old credit card to spread it around, but you need to work fast as it starts to dry.

Placed and line up edges, go to clamp it and it moves! A trick to deal with this is a small amount of salt on the glue surface to help prevent movement.

I used my straight edge to aid clamping down the inside edge as only some of my clamps were deep enough.

That basically covers all the edge panels.

The 'hinge' and 'Sliding Bolt' panel in the middle section - these work in the same principle but they need to be screwed down as the use of clamps are difficult. This is delt with in 'step 8'.

Rain was coming! I had nothing to cover up the two gaping holes where the doors were....so I painted the ply with a primer on the exterior side to give it some protection, thinking..."how bad could this be?".

It rained a lot!

The ply was mostly ok, I dried the edges off but it showed the flaws in some of the laminated veneers, so maybe it was a good thing!

Some of the veneer had lifted, so I cut this away to discover some weak wood, which I cut out and used a car body filler on. This worked rather well.

Once dry this was sanded down

I didn't want the exterior of the doors to be plain. I wanted to give the impression that these were tongue and groove built units. So I used a 'V' router bit set to cut at approx. depth of 4mm.

The panel width was divided into 6 to give 126mm centres - so 5 grooves required.

The top piece was also marked at 126mm groove and the bottom at 225mm.

My router is set onto an acrylic plate to make it easier to handle so this was set up to run between 2 straight edge aluminium bars. This was to cut the horizontal top and bottom V grooves. (A couple of the pictures show the un-painted door as I had managed to cut the 2 horizontals before I knew the rain was coming)

Once the horizontals were done then the verticals were cut. The main thing is not to overcut once you get to the horizontal cut. Also its best to do the first cut, sweep away the dust and do a second cut to clean it up a bit.

These V groove cuts revealed flaws within the veneer - small voids, so its best to get these filled with either an epoxy glue or car body filler or superglue. All work.

Lightly sand everything including the grooves and that part is done.

The mid section panels on the interior side are to thicken up the door where the hardware is to be placed. So you need to be aware of the screws or bolts that are to penetrate through. Secondly these panels are to be glued and screwed so you can't have a clash of fixings.

So how is this resolved?

A Template is required.

You need a strip of card or paper the width of the door and at least the size of you hinge - if you are using T hinges.

The aim is to transfer the hinge screw holes as well as the V groove positions from the exterior side to the card and mirror this to the interior side. Mark the door edge as to where the door hinges are to go. This is your reference point

Place the card where the hinge is to go. Mark this so you know the edge of the door and the reference point. Place the hinge exactly where its to be fixed. Mark the screw fix holes. Potentially you can drill these to set the hole position as once the door is painted you'll already have the guide holes.

Whilst still in place mark the V groove positions.

So this is your template and will work for both hinges.

Turn the door over and place one of the central panels to be screwed down. Re-align the card to the reference point - basically mirroring its position. You are now viewing the interior of the door and the reverse side of the card. You can then transfer the hinge holes and groove placement onto the central panel. This then gives you a better understanding of where you should drill the holes to fix the panel down so it doesn't interfere with the hinge holes or accidentally jut out in a V groove.

Then these can be glued and screwed down.

Potentially this step is not required but....

As end grain just sucks up water I thought I'd seal the edges using epoxy resin glue. Mix it up, smooth it on. Sets in 5 mins. Once dry this can be lightly sanded and painted over. Even if the paint is scratched then the epoxy has sealed this area.

Initially I was painting all the bare plywood with an acrylic based primer paint. Dried quick and it was what I already had.

This helped to seal up the wood and the small cracks and holes. It also revealed some of the veneer flaws so these could be rectified.

I then used an exterior satin finish paint - 2 coats. This worked very well with a small 'gloss' roller and dried fast. A small artists paintbrush was used to get paint into the corners and the edges.

Make sure you paint one side, then the other side. This helps prevent bowing in a panel.

This isnt really to do with the door build but you may have a similar senario.

The door hinges were completely rusted up. The sliding bolt was working but had layers of paint.

I thought "lets buy new hinges". Mistake.

So new ones are ordered and delivered. There's rust colour in the bag - not a good sign. The paint was bubbled in some places. Flex this, it cracks and there's rust underneath. Poor preparation that'll lead to failure in the future.

So I went back to the original rusty hinges that were 60 years old and used a blow torch on them. By putting them in oil, heating, use of a wire brush and a bit of hammering I got them back to fully working condition. Yes they were rust pitted but still more sturdy and better steel than the new ones.

The sliding bolt hardware was placed in a tub to use a paint removal solution on.

All this was then painted with a Hammerite paint in black.

So the moral is: don't discard the old - it can be reused.

Once everything is painted and dried then you can fix on the hardware.

If you predrilled the guide location holes for the hinges then that is easier. Make sure you use an appropriate screw. I tend to wipe my screws across a candle as this lubricates the screw with wax and seals the wood a little. Some screws are self drilling but I tend to prefer using a pilot hole.

The sliding bolt hardware was being fixed using M6 coach bolts. The holes I drilled for this were 6.5mm and then applied superglue to seal them internally to again help prevent moisture gaining entry.

The doors are finished and can now be fitted within the frames. As the frames were fitted first and the measurements were transferred to the door size there is no need to 'size' the door to the frame - ie planing the side down.

I used 3mm plastic spacers on the floor and spacers at the side to position the door in the frame. I use a hinge drill bit to aid centralising of the screw. You can then screw the hinge straight onto the frame.

Door stops were fitted inside the door frame - this provides a 'stop' for the door panel, aids draught prevention and mice squeezing through a gap. The sliding bolt brackets can be fitted as well.

You now have a working door.

Every project you do, you will learn from. Whether its new techniques or methods or improvements of design.

In this case I thought it may have been better to epoxy glue hardwood strips onto the edges - that would improve the edge finish as well as aid sealing the edge voids. If thick enough you could plane down to help door fitting.

But this is an exterior door that's not aimed at being a total element sealed door.

Secondly I wish I'd made the top internal hinge panel and central panel with french cleat edges - that way I could create brackets to hang a broom or shovel or other tools. Potentially you could expand the design to house shallow depth shelves to hold smaller items.

The actual making of the door was not that long - but painting and drying time was the problem - where to store out of the rain whilst this happened - so plan ahead for this.

Thanks for reading.