Insulation affecting WiFi

[HopelesslyLost]

Ive recently had an extension built, where we used foil insulation for the rooms upstairs. 
The broadband speed is significantly slower up there than it is downstairs where the router is. I have also put a WiFi booster at the top of the stairs, approx 2 metres from the doorway of the room I have the most issue. 
Does the every room guarantee covers this? My sons room does not have enough WiFi to play PlayStation etc. 

Is there a way I can counteract this issue? 
I'm assuming it is the insulation atleast, as there doesn't seem to be any other factors that have correlation. 
Any help very greatly appreciated. 

[Chrisee]

@HopelesslyLost wifi use high frequency radio waves to carry the data even a thin layer of metal will block those signals - to be flippant its how tin foil hats work. Therefore the only wifi signals will be those passing through doors etc. In such situations you need to use another way to get data to the room. The simplest is running an ethernet cable but that can often be impractical if so then a second solution is to use powerline adapters which use the home's mains wiring to do the job. 

Powerline kits start with a pair of adapters one plugs into a wall socket near the Sky hub and is connectd by ethernet. The other plugs into a wall socket in the extension. You can buy adapters with built-in wifi access points but for gaming it is better to use a second ethernet cable to the console. The two areas need to be on the same home consumer unit and work in most homes but if you buy online you can return the kit if it doesnt work in yours..

[jamesn123]

@HopelesslyLost 

The Every Room guarantee would indeed cover the room but it does not dictate that online gaming would be capable it simply states that a signal should be received in the room and that speed should be 3mbps. Whether or not it is a stable signal for online gaming doesnt matter to Sky. 

The foil insulation will indeed be the problem and as @Chrisee has already said the only reliable way to get a good internet connection there for gaming would be direct ethernet or possibly powerline if you have good electrical wiring.