Using foamboard for core of buildings

Discussion in 'Techniques' started by Dog Star, 8 April 2020.

  1. Dog Star

    Dog Star Western Thunderer

    Until now we have been constructing buildings using multiple layers of plastikard which are cut by a Sihouette Cameo. Whilst this approach does produce a really good result - accurate, strong, stable - the cost of the sheet plastic becomes a concern for me when contemplating 7mm station buildings. Enter foamboard as a possible core for a building with inner and outer layers made from plastikard - most likely the embossed material from Slaters Plastikard.

    Who has tried this approach? Suggestions / recommendations?

    We shall use UHU-Por for joining the foamboard sections... and hopefully the same adhesive for the plastikard layers unless WTers tell us that (a) UHU-Por does not grab plastikard and/or (b) adhesive XYZ is the bees knees for this style of modelling.

    Thank you, Graham
  2. simond

    simond Western Thunderer


    I used it for the bridge at the end of my old layout, covered in home printed brick paper. It was certainly structurally sound, I found that the cat made a habit of wandering around on it when I dismantled it all, there were footprints...

    I now tend to use the laser and MDF for buildings now. Not tried mixing foam board & MDF.

    linky thingy here
    Great Windowledge Railway

    Keep well
    jonte likes this.
  3. alant

    alant New Member

    I use an inner core of foamboard for 7mm scale buildings sandwichwed between embossed plasticard and plain plasticard. Make sure you use a solvent free glue on the cut foam board edge to avoid dissolving the foam core.

    *Just noticed you mention UHU por which looks suitable.
  4. jonte

    jonte Western Thunderer

    Hi Graham

    I’ve limited experience in both foamboard construction and 7mm scale in general, so not sure whether I can be if much help, but I shall try.

    Below are a couple of examples from my failed 7mm scale Cameo entry for Seacombe, Wirral.

    Station building:


    Can’t quite recall the thickness of the foamboard used (I can pop out to the model room later and check: 4/5 mm(?)), but the shell consisted of walls and ends butt-jointed with bog standard Pva, reinforced by sections of internal bracing at regular intervals. The cladding is good ol’ Wills which even in the Premier scale looks a tad on the porky side, although daylight shadowing (what?) didn’t help matters, and from memory, the brick plasticard was Slaters’. Both were stuck to the shell with the same pva glue.

    Next, we have some sort of shed affair which appeared in the background of the photos I was working from:


    Of the same construction as the station building, it’s clad in scribed veneer with a strake of balsa. The brick cladding is, again, Slaters’.

    I submit these humble offerings, Graham, if for no other reason, than to reassure you that foamboard doesn’t warp in my experience (which I hope the cobweb clad shot - below - corroborates, even when clad with a variety of materials AND on only one side :)), and can be stuck successfully with nothing more than white glue.

    Finally, the beginnings of the sole-remaining waiting shelter that never received it’s wriggly tin coat, but shown (with those previously mentioned cobwebs included) to prove the point that it stays true (all were built years before the Cameo competition which provided the impetus to try and get the layout progressing beyond making the buildings stage - without the boards or track even in place, I admit this was indeed a case of putting the cart before the horse, but that’s me ;)).

    9CFB23EC-3F8F-4ECA-AEBC-500D4A07706C.jpeg F0FCF565-993A-4491-9561-AC8F0DEBB350.jpeg

    I hope this helps, Graham.

    Good luck.


    Edit: don’t know where that green emoticon thingy came from ? . J.
  5. geoff_nicholls

    geoff_nicholls Western Thunderer

    I think I had a problem with Halfords primer attacking any exposed foam. Worth testing this first.
    Dog Star likes this.
  6. John Duffy

    John Duffy Western Thunderer

    I use a hot glue gun to join the various elements together. Most of my buildings are then either painted on directly or coated in Polyfilla but where I have applied plastic sheets I have had success with the same solvent I would use to build in plasticard. My experience is also that foam board is stable, even when covered on only one face.

    Dog Star likes this.
  7. GrahameH

    GrahameH Western Thunderer


    Ironically I have been making an overbridge during the last few days as a replacement for one I made last week.
    I posted "What's on your Workbench 2020" one which consisted of 5mm foam board and clad with plaster casts stuck on with PVA.

    Not being happy with the final build for various reasons I decided to make a similar bridge using the same core but with a brickwork finish.
    SE Finecast brickwork sheets were stuck onto the foam board using Rocket Card Glue ( never used it before but it was to hand ) and I must say it stuck the plasticard extremely well. Any edges of the brickwork were given a brush with Tamiya Extra Thin to bond them too.

    I must say that I am much happier with the result and will consider using this process again in the future.
    Here are some photographs of the bridge build in progress ( please excuse the quality David Bailey I ain't ! ).

    Initial work on scrap foam board


    Progress to date


    The wing walls are just resting as a temporary measure and need to be completed.

    Another Grahame ( with an E ! )

    p.s I also used UHU-Solvent Free in a couple of places as a test and all is fine with no affect on the plasticard as expected.

    p.p.s Rather than clog up your thread with more piccies I've posted a couple more over on the Workbench 2020 thread take a few moments ago.
    Last edited: 9 April 2020
  8. InvernessTMD

    InvernessTMD Western Thunderer

    I built a layout from the stuff! Search for Iceni Road in the layout section.
    Dog Star likes this.
  9. Dog Star

    Dog Star Western Thunderer

    Thank you for the suggestion, I have read through Iceni Road today.

    In my original post I acknowledged the use of foamboard for model buildings and the use of plastikard as an interior / exterior cladding for the foamboard. Simon (@InvernessTMD), your topic confirms that the approach is viable; what is missing from your posts is an indication of the adhesive that you have used for sticking the plastikard to the foamboard - can you remember?
  10. GrahameH

    GrahameH Western Thunderer


    May I suggest either UHU Solvent Free or my new favourite Rocket Card Glue which has a good grab to plasticard and even when using a hairdryer on my model to dry the Vallejo painted areas there is no ill effect whatsoever. I did try a test piece prior and then tried to pull the plasticard off which resulted in the card backing on the foam board being pulled away and still attached to the plasticard sheet.

    Hope this is of some use / consideration for your project.

    Last edited: 14 April 2020
  11. InvernessTMD

    InvernessTMD Western Thunderer

    @Dog Star I used good old all purpose adhesive (bostik or the own brand equivalent). It seems to have stuck the ends of the stuff without too much trouble (solvents tend to dissolve the foam). I dare say something like gorilla glue would work just as well.
    Dog Star likes this.