House Fire

House Fire

Normal House

House with Small Fire

House with Large Fire

Video Tutorial

Where to put this

As a script under the part that will serve as your button

Script

local button = script.Parent
local house = game.Workspace.BasicFamilyHome --Update name if using different house

local function burn(otherPart)
    local partParent = otherPart.Parent
    local humanoid = partParent:FindFirstChildWhichIsA("Humanoid") --Checks if player touches not some other part
    if ( humanoid ) then
        for num, child in pairs(house:GetChildren())do --Goes through house model and looks for parts
            if child:IsA('Part') then 
                local alreadyBurning = child:FindFirstChildWhichIsA("Fire") --Checks if part already has fire
                if not alreadyBurning then
                    local fire = Instance.new('Fire') --Adds fire to part
                    fire.Parent = child
                    fire.Size = 20 --Can be between 2 and 30
                end
            end
        end
    end
end

button.Touched:Connect(burn)  --Triggers function when part is touched