insulation of an old house
Hi Savy!
Second question first:Yes,it is no problem to replace the rubber strips of your aluminia windows.Bring a small piece with you and visit your window maker/seller,he will have the right strip for replacement.It could be cheaper to go to a DIY shop and check if they have it (farmers coop).If they have only some insulation strips that COULD fit then just buy an inch or two and try it out,you probably need an entire coil of the material for the house and it would be a waste of resources to buy the wrong material.There are hollow strips available -like the one on a fridge door- and there are folded ones.If the hollow one fits go for it even if it costs a bit extra.It insulates better and might last longer.
Think about replacing the old aluminia windows as soon as you can afford it,they are wasters concerning energy.Cooking pots made from aluminia are sold as "energy saving" due to their good heat conductivity.You want the opposite for your window frames.
First question:there should always be a wind breaking membrane/barrier between the insulation material and the tiles.This would have to be made of a "breathing" material like Tyvek (or something like it).The reason for this is that wind blowing in between the tiles can bring in water as well,snow or rain or fog.This must be avoided under all circumstances.
The (cost)problem lies in retrofitting:first you need to take down the tiles,than the laths .Then you put on the membrane.Than new laths back and than the tiles.After this job is done you can put in insulation material between the beams.
Get a DIY book to see exactly how it needs to be done,there are to many little details to explain here.Collins DIY manual or something like.Don't safe on the insulation,it will pay back it self very quickly.Once you are on the job check the beams if they are rotten and need replacement,the laths are not to be used again but the beams could be fine for another generation.Working on the roof is not exactly a DIY job for someone who is not experienced,but bringing in the insulation should be fine-maybe with someone who has done it before.Stay away from offers that would use polyurethane foam sprayed on the inside of the roof,this will certainly ruin your timber within a short time due to rot.Timber can get wet if it can dry as well,but enclosing wet timber from three sides with a non breathable material will almost certainly cause it to rot.