How to attach insulation and plyboard to a shed walls and ceilings?

Taf

Hi there.

I'm looking to insulate my shed and also to line the walls and ceiling it to make it a more user friendly workshop.

I have done some research and it would appear that Foilboard is the way to go, and after much research, I will also make sure I have airgaps between the Foilboard and the exterior walls and ceiling of the shed.

My questions are,

1. How do i attach the Foilboard to prevent if from sagging - what fasteners/fixers should I use and where should they be placed.

2. How would I attach the Ply sheeting to the shed frame/ ceiling etc. once i have already applied the Foilboard. Do i need to build a wooden frame for the walls and ceiling  that  I would then attach the ply to , or can I attach the ply directly to the ceiling and wall framing that is noted in the pics 

3.  Would standard plyboard  be ok, or should i be looking at a marine grade ply? and would that marine grade ply be to heavy.

I have two weeks off work at present and I am hoping to get a good amount of this project done in that two weeks, so any  advice would be greatly received. 

I'm keen to give this a go, but have just enough DIY skills to know that the pointy end of the screwdriver is sharp, so if it hurts i am holding the wrong end , so if you could please keep the answers simple as possible ( no jargon) then it would be much appreciated.

Thanks in advance 

MitchellMc

Hi @Taf,

It sounds like a great project and you are definitely on the right track with your research. You might also find it helpful to have a look through some of the existing shed insulation discussions on the community, as there is a lot of good, practical information already shared by members who have done similar builds.

Foilboard is typically fixed directly to the shed wall and roof sheeting using foilboard spacer blocks and silicone, not screws or nails. The spacer blocks are glued to the back of the Foilboard using a clear gutter silicone, then the spacer blocks are glued to the metal shed sheeting with the same silicone. You hold the sheet in place until the silicone grabs and then allow it to fully cure. As long as you use enough spacer blocks across each sheet, the Foilboard will not sag. No mechanical fasteners are required for this part of the installation. Here's the installation guide.

How you attach the plywood lining will depend on how thick the ply is and how far it needs to span. Shed wall and ceiling frames are often spaced quite widely, and thin ply will sag if it spans too far without support. In most cases, you will need to add timber framing, such as 75 x 35 pine, fixed between the existing shed framing to reduce the span and give you something solid to screw the ply into. Once that timber is in place, you can fix the plywood directly into the timber framing behind it. For ceilings in particular, it is very important to check with the shed manufacturer that the structure is designed to handle the extra weight of insulation, timber, and plywood, as not all sheds are engineered for lined ceilings.

For the walls, standard plywood is usually fine provided your shed is weatherproof and you are not getting water ingress. Marine-grade ply is much more expensive and generally unnecessary for an internal shed lining. It is also heavier, which adds more load to the structure. A good approach is to use standard ply and then paint or seal it, which will protect it from moisture and make the space brighter and more durable.

This is very achievable as a DIY project, but it does sit more in the intermediate range, especially when working overhead and handling large sheets. There is no shame at all in getting a second person to help, or even calling in a handyperson for parts of the job, as ceilings in particular are much easier and safer with two people.

One final note for our New Zealand readers, foilboard insulation products are not permitted for use in New Zealand, so always check local regulations before starting a similar project. 

Please let me know if you have any questions.

Mitchell