Once the frame is up and you’ve enjoyed looking at it, work can begin on closing in and making it watertight. One of the advantages of taking up the frame to include the rafters means that work can begin immediately on the roof, creating a dry work area whilst at the same time allowing the green oak to start gently drying out.
For a garage or cart shed this can be simply nailing larch, douglas fir or oak weatherboarding directly to the frame and battening the roof rafters to take slates, tiles or tin.
Habitable frames require more complex wall and roof build ups which will have been detailed at the design stage. The main consideration will be whether or not you are intending to expose the oak frame externally.
Although it is possible to insulate “panels” between the oak frame in “half – timbered” style, it is worth carefully weighing up the weatherproofing and insulation implications of such a building method. Firstly, timbers that straddle the wall are prone to “cold bridging” and will let the cold in and the warm out! Secondly, and perhaps more significantly, the green oak frame will shrink away from the panels over time as it dries, and a fiddly panel construction system will have to be installed with a weatherproof expanding gasket that expands to fill the gap. It can be done but there is a greater risk of air and water getting in.
At Castle Ring we encourage people to use the structural frame as the skeleton from which the building envelope can be hung getting the best of both worlds – a beautiful frame on the inside, and a warm, waterproof skin on the outside.
Typically an impermeable envelope or skin is fixed to the outside of the frame keeping the weather out (even as the oak shrinks and moves when drying) and the insulation in. This envelope can be constructed of a multitude of different materials with various insulation options. The choices to be made are tricky and will be affected by many things including cost, aesthetic preference, environmental impact and the thermal performance of your house.
We are happy to talk through these options with you. Externally the building can be finished with weatherboarding, render, stone, brick or any such combination.
Vaulted ceilings exposing dramatic roof spaces are made possible by covering the oak rafters with tongue and grooved boards and placing the insulation on the outside of the structure. Alternatively you may wish to insulate between softwood rafters finishing with an internal plastered finish.
Underfloor heating works well in oak framed buildings as it gives off a gentle, steady heat allowing the frame to dry out more slowly. This may be set in a screed on the ground floor topped with stone slabs or tiles. On the first floor, underfloor heating can be contained within the floor build up above the joists for a solid wooden floor or chipboard and carpet.
We can advise on the various glazing options, joinery, heating systems and insulation, cladding, flooring and lighting to make the most of your timber framed home.