Cavity between window and beam

[NatalieA]

Hello

I’m very new to this we purchased a 17th century cottage back in November.

I’ve spent hours and hours of research the best approach to start tackling the maintenance of this property but I’m still after some advice.

I have leaded casement windows and they seem to have been filled with cement in the cavity between the frame and the oak beam. This is now failing.

What would be the best way of filling the gap?
Many thanks for any advice

 

[skierhughes]

I use Oakum in the middle and lime mortar on the inside and outside.

 

[Cubist]

To properly and safely (by preventing damp ingress to the woodwork) fill the gaps between the frame timbers you will first need to densely and tightly pack them with oakum and/or caulking cotton which is then finished with a 3-5mm skim of either a lime mortar/plaster filler both indoors and outside. Outdoors you could alternatively use a burnt sand mastic for the skim but this is more difficult to make for yourself and can fail quickly if improperly prepared. Oakum is a trifle expensive as it is sold in small 3-5kilo bales and can cost around £100 or more today while Caulking Cotton is typically sold for around £10 for a 0.5kilo ball. Both can be purchased from Boat Chandlers. Oakum is typically made of long strands of jute - typically stripped from old ropes - which are then loosely formed into a new rope of widely varying thickness and then soaked in Stockholm Tar - this rope can be thinned by hand or braided with additional lengths to produce a final thick rope that can be hammered into place. Caulking cotton is sold in various thicknesses but is commonly available in a 8mm diameter which can also be braided to produce a thicker rope as needed. The sellers will perhaps suggest you purchase some rather expensive 'caulking irons' for the job of hammering the oakum or cotton into place - don't bother with these; an old dull bolster chisel, a wide bladed flathead screwdriver, an upholsters tack lifter and a mallet is all I use.

Installation will require that you remove all the remaining material used to caulk the joint lines between the timbers and the wooden frame(s) - particularly any cement mortars or gypsum plasters. The oakum or cotton is then pushed and hammered into place to completely fill the gap while leaving a 3-5mm trench/rebate that can then be filed with the appropriate skim material.

You should consider exploring the full perimeter of every window and door frame to determine if similar treatment is required. You should also closely examine the old peg holes and joints between the frame timbers to see if these are in need of any repair or additional caulking. BTW - if that's a cement mortar render outdoors you should closely examine the sections of the frame where it was been covered with the mortar - like that at the foot of the post next to the window - as there can be nasty surprises hiding there.

 

[Kearn]

As said above, oakum and lime with a decent aggregate depending on the gap width - oakum needs to be very tightly twisted before being hammered in. Nice to see correctly installed windows, oak wedges to pack and there will be some big old screws hidden somewhere.

What I’d be focusing my attention on though, is the state of the timber frame encased in cement and plastic paint. There’s quite possibly a whole lot of work waiting there…