is there waterproof insulation. EWI?

hail hail

Private Member
Small job at my own home. Changed my dining area, kitchen etc.. at the start of the year and had to open the floor to run new heating pipes. This came close to the side double doors. Filled back in with s&C however i couldnt get any insulation under the double door. Its only a few inches high! On the outside under the door but above the step i hadnt closed this off with s&C. Just being a lazy f**k*r all year by putting it off. Anyhow, now that some mice have got in with my lazyness, ill be closing this off in teh next few days.

What i want to know, is there any waterproof insulation boards that i can put under the door. I d say i have a 4-5 inch debth that can be filled. I was hoping some insulation then s&C to close this off rather than just filling with s&C. Will get pics later


Active Member
I think what you require is a extruded poly, although it is better at moisture resistance it is not 100% so would need a waterproof coating also.