So I've just ordered 55 square meters of this kit for tiling on. Not being a tiler etc I just took the companies word for it that you can tile straight onto the foil topped boards after using the multi purpose primer neat? Both tilers have expressed concerns about tiling onto the foil top. Does anyone have any experience with tiling onto these boards? ProWarm LoFlo LITE Dual Purpose Panel 1200 x 600 x 20mm If anyone does can you please advise me if it actually works?