Oak and Accoya windows

[merlin]

Has anybody had any success in gluing Oak to Accoya and making windows and doors out of it?

I have been asked to make some Oak window frames, the finished section has to be 4 1/4" square cills and head with 4 1/4" x 3 3/4" mullions and jambs.

The existing are all solid Oak but are painted inside with a dark stain outside, this flavour will be repeated on the new windows.

Just the cost of the Oak in solid will be frightening let alone the availability in that sort of size and when the inside is going to be painted it seems a bit of a waste. so would laminating Oak to a Accoya be an option?
What with the fact that Accoya doesn't move much and Oak does would that be an issue? Any opinions would be appreciated.

Merlin

 

[RobinBHM]

Ive made oak windows in big section before by gluing 2 or 3 pieces together, ie a home made engineered oak.

Back when American white was a lot cheaper than European I made the outside European and inside American.

If you have plenty of sash clamps its possible to glue a stack comprising of 3 or 4 sets all together.

I found the easiest way is to machine the lams a bit oversize in width and thickness, so the glued up piece is around 6mm -10mm oversize. Then put through 4-sider to finished section.

You can make your window frame section out of 2", 2 1/2", 3" which is much cheaper than getting 4" or thicker oak.

When constructing orangery frames we routinely laminate up iroko sections with no problems and much better than struggling with less stable 4" boards.

Laminate so the join is in the rebate and try to avoid the glue line where a rubber groove will go.

Mixing species like oak / accoya is risky due to differential movement. A major timber supplier tried making engineered softwood with the outer lam in accoya, result: banana /propellor /donkeys hind leg

 

[ComfortablyNumb]

I made a new t&g front door and frame from engineered oak the Brooks Bros make. I don't rate it because Oak wants to move so much if exposed to sunlight it cracks more along the laminate glue joins. Not sure what type adhesive was used to make up the sections but my door cill was made from 3 sections and consequently I have 2 unsightly cracks on the joins that even though I forced pu glue into and drilled and pelleted a 6x120mm screw through keep appearing. All the joints I made and glued are sound but that's probably down to me using domino XL and doubling up .The whole job had 2 coats of ebony Sadolin classic then 2 coats of Sadolin SupaDec on top so I can't blame that. I just think Oak will do it's own thing and you have to allow for it

 

[Jacob]

If the oak is going to be painted and dark stained it seems a waste of expensive (and not too durable) wood. Better to use redwood and paint that - WITH LINSEED OIL PAINT! all other varieties are useless. You can get it in shades of sh*t brown if that's what you want.

 

[merlin]

Thanks Gents, kind of what I thought.

I will have a rethink and sit down with the client to see what the options are.

Merlin

 

[LBCarpentry]

I'd just laminate the oak straight together. No messing with accoya, from what I know the prices are the same anyway (?) for your cill sections glue up
3" x 5" & 1.5" x 5". And for the Jambs you want 2.5" & 1.5". PU glue and plenty of cramps. Keep the thinner laminations to the inside as the (potential) glue line will be painted.

I wouldn't even pull the client into it as it brings in doubt. Just say "yes we can do that" and crack on. Happy days

 

[Treecraftwoodwork]

We have been laminating Accoya to European Oak for a few years now with no issues at all. There's a large demand for oak windows/doors with a clear finish. However oak with any clear or translucent finish will stain black when exposed to UV. There's also an issue with movement with oak anyone that has laid a solid oak floor will know this. Our solution is to laminated Accoya for the outside and European Oak on the inside, finishing the items with clear internally and an opaque finish externally. As already mentioned you will need to use PU when gluing and remember to score the oak on the glued face every 100-150mm to give stress relief.

There are down sides to using Accoya. The cost is around the same as good quality European oak. Accoya is highly acidic so stainless steel fittings are essential. Accoya is actually a brand name not a species of timber, the timber is Radiata pine grown in New Zeland. The process of acetylation involves drying the pine down to very low levels of moisture then flooding it with vinegear. The drying of the timber release/causes shakes which will become apparent when the timber is machined. Once a shake has been filled it will not open up again. Accoya takes an excellent finish after painting.

Before fitting Espag window locks or Multipoint door locks, coat the inside cavities with an endgrain sealer to reduce the out gassing, if not the vapour combined with the moisture in the air will munch through a lock in a few months.

The off-cuts are great for lighting a stove with, it burns a doozy and honks of vinegear :roll: