Door frame damage

[erikwoolf]

One of the external doors has been subject to few years of water damage and the lower parts of both sides of the frame need to be replaced. The previous owner had already replaced the door once (because of water damage!) but retained the old frame and there seems to be a double frame around the door. I am trying to figure out what kind of wood I should use to replace them, if possible avoid using pressure treated.
Also how to manage the 1.5cm gap (foam?) behind the existing frame and external wall (currently fitted with old newspaper..) and finally do I need to install some form of DPC at the bottom of the new frame? It rests on the concrete(?) cill of the door but I am not convinced it is not getting in contact with damp from the bottom.

 

[Zebra]

You could try an "off-the-shelf" frame from a DIY shop, but if it's an old door then measurements might not be right.
You could get a local joiner to make something up for you - a good quality softwood such as Douglas fir would be fine, or oak if you want to go mad...
Or you could make it yourself, sourcing the timber from a woodyard...
If it were me I think I'd get a quote from a local joinery shop at least, before looking at the other options.
In terms of gap-filling, yes, this is one place where foam might be appropriate, but what's horrible about foam is the way it sticks to the old bricks. If you can fit the frame well, and the gap is no wider than a cm or so, then exterior frame sealant, available from DIY shops, would be better in my opinion. Any gaps within the wall, away from the exterior surface, could be stuffed with glass fibre or something like that.
In terms of DPC, it depends what is beneath it. The door frame doesn't necessarily need it. As long as its bottom isn't sitting in a puddle, then whenever it gets wet, it will get dry again. However, if the house has a DPC, then it would be sensible to continue that beneath the frame. Or if there is dampness potentially arising through the tiled floor, as you say, then protecting the frame from that would be an advantage and certainly no harm. I probably would be tempted to insert a piece of DPC under the frame, turned up the wall for 200mm or so, trimmed flush with the front and hidden within the frame sealant. I might even be tempted to have a tiny stone plinth - is there the remnants of one beneath the existing frame? - to raise the timber of the frame up off the ground a bit.

 

[88v8]

One of the external doors has been subject to few years of water damage and the lower parts of both sides of the frame need to be replaced. The previous owner had already replaced the door once (because of water damage!) but retained the old frame and there seems to be a double frame around the door. I am trying to figure out what kind of wood I should use to replace them, if possible avoid using pressure treated.
Also how to manage the 1.5cm gap (foam?) behind the existing frame and external wall (currently fitted with old newspaper..) and finally do I need to install some form of DPC at the bottom of the new frame? It rests on the concrete(?) cill of the door but I am not convinced it is not getting in contact with damp from the bottom.

I presume the original frame/door was bigger and filled the whole opening. Later it was replaced with that smaller frame/door you have in there now, perhaps a take-out from elsewhere. The double frame was an expedient to fill the opening.

So you could have a new door/frame made the original size.

Yes, slip a bit of dpc under the feet of the new frame, and put a three-coat paint system on the end grain before you install it.

 

[aockenden]

If you want a natural, more eco-friendly alternative to the spray foam gunk for the gap, we used a combination of sheepswool and pine-tarred oakum for the sizeable gaps between our new window frames and the rough stone of our window reveals. Which we then “sealed” / covered over with a rich mix of NHL 2 and sharp sand on both inside and outside (if I were doing it again I would have added some fiber like horse hair to the mix to improve flexibility to handle differential movements between the window frame and surrounding stone).

The tar in the oakum will bleed a bit into the capillaries of the lime, so you may want to wait for it to settle down before lime-washing over the stains. Alternatively you can get untarred oakum, or caulking cotton, or just stick with the sheepswool. All of them will be insulative.

 

[Toby Newell]

Oak or meranti are the most common species in commercial construction. Nothing wrong with pressure treated softwood that I know of. When I have done such repairs I always fit a little dpc. More importantly is to sand and coat the end grain as someone else said. I have a irrational hatred of expandable foam so can't comment on that other than we managed to build stuff for the last 10,000 years without out it quite successfully.