How to build a mushroom cubby house?

[Polka-dots96]

 NOT MY IMAGE- photo for inspiration

Hi! I’ve been asked by my kids to make a mushroom house! I’m pretty handy and creative (and if I can pull it off they’ll think of me as a fungi) but I’m stumped on how to do it (or it could be there’s too many other ideas in my head and not mushroom for this one) 😂

Anyway, criteria for roof options are

- I want to be able to mold it to have that curvy mushroom shape

- needs to be easily/cheaply water proof

- not too heavy! I don’t want to have to build a super complex frame to safely support the structure!

Last night I remembered expanding foam, not a product I’ve previously worked with, and am wondering if that would work?

Id build a pointed roof frame, chicken wire to make the shape, fill with expanding foam, smooth and paint?

Would this work? Anything I’d need to consider or do to make it last? Or another option that would be better?

thanks!!

[JacobZ]

Hi @Polka-dots96,

A warm welcome to the Bunnings Workshop community, it is wonderful to have you with us.

It is certainly an interesting project. I think the idea of using chicken wire with expanding foam, like they do with parade floats, would likely be the best option, as it would be relatively strong while still being lightweight.

As the walls would need to support the roof, my biggest concern would be how to build the walls, so that they are sufficiently capable of supporting the roof. Using lightweight reinforcing mesh like this Jack 1800 x 1000 x 200 x 7mm Reinforcing Mesh Sheet to create the walls might be a good option. It would have less flex than the chicken wire, so the walls couldn't have as complex curves, but you could still curve it similarly to the photo.

You could then connect the roof and wall mesh together with something like this Galvanised Tie Wire to ensure they stay together well.

From there, you would apply your expanding foam to the mesh and roughly shape it with something like a Jab Saw, then further smooth and shape the surface with a Surshape Plane.

You should then use 3 coats of a high-quality exterior paint such as Dulux Weathershield to colour and protect the foam from the elements. 

Allow me to tag @Dave-1, @Noyade and @Nailbag to see if they have any thoughts or ideas.

Let me know what you think.

Jacob

[Dave-1]

Good afternoon @Polka-dots96 

I think you win todays prize for outside the box thinking  

I do like the mesh that @JacobZ has suggested as it will give somthing to support the roof. Just tring to fig how to keep it bent in an arch for the stem of the mushroom. You could tie wire between the bottom edges and also the top. The chicken mesh could could use standoff wire to give that gap for the foam to sit within and some body for the walls.

Making a domed roof, mmmm How about a 3 step approach.

Using something like Fountain Products 880 x 880 x 220mm Green Deluxe Sandpit with a plastic bin on top, tie the two together with wire. You have a basic shape of a dome, then you could use the chicken wire to create a smoother dome to your liking. 

Some probelms I can see tho not sure how to combat them.

Rain, waterlogging the expanding foam. 

Paint reacting with the expanding foam. (Maybe something you can spray first and then spray paint after its dried?)

Wind blowing the structure easily. You could have some rods that extend from the ground up the walls and through the "cap" that can be tied down with the camping eath screws.

As an alternative to just expanding foam, how about pool noodles? They would be easy to tie to the metal mesh (Id use wire over cable ties a sthey will perish in the sun) You could also use the pool noodles oon the roof structure for fill so its not a straight dome but more contoured?

I would start with the detachable roof first, I think it will be the hardest to solve and if you cna do that then the walls should be easy as.

Dave

[Noyade]

I've been Googling.

One site says it's fiberglass and weighs 276 kg!?

Might be worth contacting these people in Queensland for a quote - just to be see what we're up against.

My thought was concrete as the medium - steel rods and form-work with gradual layers. The top would be separate and lowered into position - with a crane! 😁

[Nailbag]

Hi @Polka-dots96 

A very creative Star Wars nut mate of mine created a life-sized X-Wing fighter primarily out of chicken wire and plaster of Paris. It was exceptionaly strong and looked amazing once painted up. I think the same construction would be idea for your mushroom cubby.

His X-wing fighter was donated to our local drive-in ticket office which is one of only a handful remaining in Australia.

Nailbag

[Jason]

I've admired it many times @Nailbag. A fantastic creation.

Jason

[Nailbag]

Hi @Jason ,

It was made originally for his 40th with which was a long time ago. Of course it was a Star Wars themed party. Not a bad effort for a Vacular surgeon by trade!

Nailbag

[Noyade]

We were there in 2015.

Watched Unbroken.

https://en.wikipedia.org/wiki/Unbroken_(film)

But I don't remember the X-Wing?

Awful experience.

My wife took many photos - she is searching as I type.

That was the night I realised maybe 80% of Australians drive something as large as a Toyota Prado.

We could barely see the screen from out of a humble Falcon. Kept moving, but another Prado would park in front of us.

😐