insulating a timber frame porch

[moomoojaj]

I am building a small porch with a timber frame construction. I am confused as to the best way toinsulate the walls. I have been told that solid foam 'batts' are better than fibreglass. What about a moisture break?Please advise.
Thanks in advance

[buildersmate]

With four external walls and a floor, I wouldn't have got too hung up on insulating it unless you are planning to put heat in there for a specific purpose, like somewhere for the dog to sleep at night. However insulation is cheap. If you are talking about the double foil sided foam sandwich then, yes, they have a much higher insulation value (about 2x). You can get them in various thicknesses at 10mm intervals and 50mm works a treat inside the cavity. Unless its going to experience high exposure to driving rain on the outside, the moisture won't come through the foam insulation. Porches are not covered by Building Regulations.

[buildersmate]

Sorry, I didn't read the timberframe bit properly. Yes, I'd put poly sheet between the outside of the stud frame and whatever you are putting on the outside (shiplap or similar?)

[gasman]

You need to put a Moisture Barrier on the external side such as roofers felt etc. before the cladding goes on, this will still alow the timber to breath and eliminate it from sweating... The Vapor Barrier (Visqueen ) ect... needs to be on the internal side before the plaster board is fitted & Kingspan or foam batts as you put it is placed in the middle of it all. The easiest way as i was told of remembering this ( still can hear my old building college lecturer's voice in my head ) is that the vapour barrier has the letter P in it so goes on the Plaster side