insulation help

hi.
i have a timber frame bungalow built in 1964. it is not standerd timber frame tho because where the windows are there is no external blockwork. just timber cladding on the 4" internal timber frame. there is felt membrane behind the timber cladding and like a 3/4 mulch board. that does cover all the timber frame.
There is no insulation at all tho in the walls of the building.
I was wondering what the easiest way to insulate the whole house was.
i also need to insulate the internal walls aswell.
So was thinking of toataly gutting the inside and starting again but i dont want to leave the outside at 4" where the windows are either.
Any adivice gratefully accepted.

Hi

The solution would be (working from the inside) remove wall coverings/plaster/plasterboard to expose timber frame. Then install 50mm thickness insulation [either PIR or Polystyrene] batts between studs, then add vapour barrier across the face of the studs and overclad the studs with something like a Kingspan K17 insulated plasterboard, thickness of insulation will depend to a certain extent on how much space you are willing to loose, but should be a minimum of 50mm.

Tape, Joint and Decorate to finish.

As for the internal walls, you should not need to insulate these as over time steady state heat losses will/should balance out between the rooms and the important part to remember is that its the external walls you need to insulate. The other area's that suffer heat losses are the ground floor and the roof. Glazing isn't particulary good, in fact its bloody useless, however the area of glazing is usually minimal when compared to walls, floor and roof therefore the heat losses are not that significant, unless of course you have draughty windows, in which case replace with double or tripled glazed units. If you have money to burn you can even get tripple glazed units which have quite an impressive U value!

Regards