How to build a trap door into existing decking?

[jd15]

 

 

Hi all,

I couldn’t find an existing thread so reaching out with hope.

I have a fully enclosed pine deck and I need to a quick access point for sewer and stormwater lines. 

Grateful for your ideas and tips on how to create a simple, low skill required, trap door within the deck? Please note that I have minimal skills and tools so a simple (not perfect) solution is required.

I propose using my jigsaw to cut a square in 4 planks and then bolt in a pine frame and hinges.

thank you in advance 

[JacobZ]

Hi @jd15,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

While it might seem pretty simple to add a trap door, the fact that it needs to support any of the weight applied to it could make it a bit trickier than you think. It should still be achievable with some basic tools and know-how, but we need to ensure it is strong and safe.

Do you currently have access to the underside of the deck at all? Do you know what size the joists are?

You'd have to start by building a basic timber frame that the decking boards will attach to. 70 x 35mm Outdoor Framing H3 Treated Pine should be fine.

We'd also have to attach some 90 x 45mm Outdoor Framing H3 Treated Pine to the decks joists. The frame of your trap door will sit on top of this when it is closed. It could be attached to the joists using galvanised bolts. This will ensure any load applied to the trap door is then transferred into the joists, ensuring it is safe to step on.

You will also have to attach some framing that runs between the joists to attach your hinges.

This design would ensure your trap door is well supported and safe to step on.

Let me know what you think.

Jacob

[jd15]

 

Hi Jacob, thanks kindly for the response and incredibly helpful photos. 
This suits what I had in mind and looks achievable.

I don’t have access to the underside of the deck as it’s fully enclosed and the side beams cover majority of the fascia preventing any options for a side entry.

the joists look like they are around 360mm apart and appear to be around 50mm width.

[JacobZ]

Hi @jd15,

It's more the height of the joists that I need to see, which would be difficult without lifting a board to see it. 

You could hang a string down through the decking boards, visually see where it passes the bottom of the joist, then pull it up and measure the string.

I need to know the height of the joists so I can ensure that the timber framing would be able to fit height-wise.

Joists are often 140x45, so if that was the case, you should be able to use the timber I mentioned above.

Let me know what you find.

Jacob

[jd15]

Hi Jacob, 

I tried the string approach but I don’t think I’m doing it right

After I took away the board thickness of 20mm, it looks like the joists look is only 80mm in height. Could this be possible? I will attach a photo

 

i might pull up some boards this weekend and get back to you 

[JacobZ]

Hi @jd15,

It could be 90x45, which would make things a bit trickier, but it should still be doable.

I'll be online this weekend, so if you decide to pull up some boards, let me know what you find, and I'll be happy to help out.

Jacob