How to extend raised concrete verandah?

[mindnmetal]

I have a raised (about 1100mm high) concrete verandah at the front and back of my house. Its over 50 years old, has patchy pebblecrete (that I hate) and big steel framed roofs held to the facia with roofing screws.

I would really like to extend both verandahs to make family friendly outdoor spaces and just looking for some advice. I have looked into building a merbau deck over the top and extended out but the clearance between the concrete and the entry doors for the house is only 70mm and the pebblecrete makes the surface very uneven.

I like the idea of extending the concrete deck and getting it polished, but not sure how I could create a raised concrete deck.

I am hoping to extend the deck out to the right in the picture below (over the raised garden bed that the local stray cats use as a toilet).

Any ideas or advice would be greatly appreciated.

[MitchellMc]

Welcome to the Bunnings Workshop community @mindnmetal. It's fantastic to have you join us and many thanks for your question.

You'd be correct in saying that 70 mm is generally not considered enough height to build a deck in. Something like Treated Pine Outdoor Timber Framing 90 x 45mm could be laid on its side, giving you enough room for a 19 mm decking board on top. However, this would only leave a 6mm gap for drainage and airflow underneath.

It would be worth considering demolishing that concrete slab and building a deck over the entire area. The bricks wouldn't necessarily need to be removed, just the 100mm top slab. This would give you enough room to build a low-level deck where the slab was and then extend it out on posts.

To extend the concrete slab, you're looking at some engineering that would quite possibly require a professional's services.

Let me mention @maccifo, @pepsp, @diy_hausdesigns and @Dilanka to see if they would like to join the discussion.

I look forward to following along with you build and offering assistance.

Mitchell

[pepsp]

Hi @mindnmetal welcome to the community. Sounds like a great project you’re scoping out. What is the size of the existing verandah?

I’m certainly not a qualified tradie but I agree the clearance seems small to go over the top of the existing concrete. Having said that, this Family Handyman article provides a description of how it might be achieved. Use of a waterproof composite decking material might help deliver an outcome that should last longer in difficult drainage conditions.

Looking at the photo the top slab doesn’t look very thick. What is the condition of the existing concrete? I can see a corner of the slab has chipped off next to the metal railing. Are there any other cracks etc or is it sound?

If it’s sound and you’d really like to keep the concrete, just with a different look you could consider resurfacing. It’s possible to DIY and would give you a chance to have the old section and any new ones look similar.

Alternatively if the concrete isn’t in great condition or you would prefer a wooden look you could investigate how hard it would be to break up the concrete slab but leave the bricks in place. A couple of posts I was reading in other forums and handyman magazines talk about hitting a corner of the slab with a sledgehammer to see how easily it breaks to help make decisions about demolition approach. If that’s a bit too destructive you could try drilling some investigation holes. I like doing my research first and knowing what I’m up against.

I can’t comment on how to do a concrete deck extension- sounds out of reach for an average DIYer like me. I suspect either going over the top with something that will deal with the low clearance or taking off the existing concrete slab top and building a timber deck is the easiest way forward.

[pepsp]

Hi @mindnmetal  I had another idea if you want to avoid demolition. You could consider a product like Stratco decking tiles over your existing veranda then build out a deck that extends to your preferred extent and use either the same or contrasting colour decking boards depending on the look you’re going for

[pepsp]

@mindnmetal one more idea for you mate. Check out this Klevaklip patio decking system Has given me an idea for my own horrible 1960’s pebblecrete patio!

[lost89577]

ok, need more photo's so advice is limited

first off what type of deck to you want, because if you want tiles the exposed aggregate concrete slab just needs to be cleaned properly to accept tiles. then you can extend in concrete or concrete decking sheets

Also the veranda roof has caused the eaves to rot, this will need to be repaired and i would suggest a new veranda roof too. the guttering changes should also considered too. when building over the raised garden bed, make sure to empty or remove it as it will cause issues as it will retain water.

[Jason]

Many thanks for joining in the discussion @lost89577. I'm sure @mindnmetal appreciates the feedback. It sounds like you have a lot of knowledge and experience you can share with the Bunnings Workshop community so we are looking forward to seeing more posts from you soon.

Let me extend a very warm welcome to the community. We're so pleased to have you join us. Please don't hesitate to post anytime you have something to share with the community or need a hand with a project around the house and garden. We have helpful, clever and creative members sharing wisdom and inspiration on the site every day so we're sure you will get as much as you put into the discussions.

Please let me know if you ever need a hand getting the most from the site, or have any feedback about how we can improve Bunnings Workshop for you. 

Thanks again,

Jason

[lost89577]

thanks for the welcome Jason,

i was also thing think the veranda extension could be tiles for existing area and timber for the rest a this has become more common these days. this would be cheaper and easier then concrete slab extension.

Also think about adding stairs because if you are going be using this area more often you might want better access to the grass area without having to go though the house.