Hand is forced - new decking required

[Mjward]

What a beautiful outlook.

The paved area looks quite large, have you considered the possibilty that the loss of the decked projection altogether might not be such a huge thing if you could optimise the design and use of the paved area? I guess that's probably too radical. Rather than have a large structure going down to ground level, if you could get good fixings, would it be possible to substitute a cantilevered steel structure which could give you plenty of options for flooring. It would need a structural engineer to design it but might be more economical in the end. probably all sorts of reasons why not , but just thinking aloud really.

Jim

The view is a substantial improvement on what I used to look out on to when living in London
It had crossed my mind Jim whether to sack off the decking but the more I analyse the space the more I can see why the previous owners opted for it. Just gives enough space for tables/chairs and other items etc without getting in the way of walkways and so forth. I like the idea of a cantilevered structure, infact the garden company who has come to quote thought the existing wooden joists were cantilevered under the patio but in fact they are braced into the stone work underneath. Suspect if this was the only project on my plate I'd definitely investigate that route further but this is 1 of 100+ (house of horrors!) so for now I'm going the "basic" route but hopefully one that lasts my time at the property

 

[johnny]

What a beautiful outlook.

The paved area looks quite large, have you considered the possibilty that the loss of the decked projection altogether might not be such a huge thing if you could optimise the design and use of the paved area?

Jim

yes that was my first thought too Jim when I first saw the pictures.
Surely such a small jetty decking is not worth the huge cost quoted

 

[Mjward]

yes that was my first thought too Jim when I first saw the pictures.
Surely such a small jetty decking is not worth the huge cost quoted

To confirm it's both areas of decking, the jetty in pictures 2&3 as well as the large decking at the rear of picture 1. Approximately 40sqm in total

 

[Mjward]

Right...decking company came back last night, quoted incorrectly (used price on cheaper boards vs samples they sent) and will be extra 1200 i.e. 12k in total now. No idea if this is a simple honest mistake or a reaction to the fact I didn't haggle on original quote and the "squeeze" has begun. Either way it's enough to make me think and I'm rushing into this. As per your suggestions above, I need to think about layout/space usage & requirements vs just copying/replacing exactly what is already there. I need to get more than one quote although I've been badly burnt from checkatrade et al, local FB groups etc, this was the first direct recommendation from my local timber merchant. Additionally, given the weather has already turned, we aren't going to be getting any use out of it for 8 months+ now, so better I leave it so that the weather is better to build it in and I'm not wasting a year of it's life doing nothing.

That all said, I still have an immediate safety issue with it. We have a puppy that still goes multiple times a day and it remains quite literally a poop deck, i.e. I still need to walk on it to pick it up etc. Large parts are absolutely fine and stable, as are the joists (no spongeyness/spring etc) but there are small sections of decking that have rotted to the point they would break with direct pressure.

What I am thinking, to get through 8 months, is to lay a few sheets of board down to spread any load. I've not used it before put would OSB Type 3 work for this purpose? Would it need waterproofing/painting to survive 8 months? Local merchants stock it in 11/15/18mm, guessing for the intended purpose 11mm would be fine or would you recommend thicker?

 

[TomGW]

How much of a drop is it on the outer edge? Having now seen your photos it making me think about a strip foundation and supporting wall along the outer edge with a 'T' beam and block floor that can have slabs to match your existing paving. This avoids the need for a retaining structure and fill. Blocks and T beams are all manoeuvrable by hand in an inaccessible location.
The other concern - where exactly is your property boundary? If it's the hedge and critically the centre of the hedge, then the previous owners may have annexed a bit of the neighbouring property, by extending to the outer face of the hedge. Just a thought.

 

[Mjward]

How much of a drop is it on the outer edge? Having now seen your photos it making me think about a strip foundation and supporting wall along the outer edge with a 'T' beam and block floor that can have slabs to match your existing paving. This avoids the need for a retaining structure and fill. Blocks and T beams are all manoeuvrable by hand in an inaccessible location.
The other concern - where exactly is your property boundary? If it's the hedge and critically the centre of the hedge, then the previous owners may have annexed a bit of the neighbouring property, by extending to the outer face of the hedge. Just a thought.

Solid thoughts but...... the drop is almost a sheer 30m down to a river. I would be a lot more inclined to take on the decking work myself if heights weren't involved. On the boundary front it's not clear, arguably we own the land to the point it touches the river. Previous owner was a solicitor (for whatever that's worth!) so hoping she was on the ball when she came to the same conclusion.

I think I will give the whole thing a big think re permanent solution. I am also wondering if I just keep the existing structure, replace the decking boards myself like for like and try and figure out the railings as cheaply as possible. That said, I do like the idea of extremely low maintenance composite, just don't like the price.

Either way, think for now will get some OSB on the main decking area to spread any load and render it "safe" until spring!

 

[yetloh]

Solid thoughts but...... the drop is almost a sheer 30m down to a river. I would be a lot more inclined to take on the decking work myself if heights weren't involved. On the boundary front it's not clear, arguably we own the land to the point it touches the river. Previous owner was a solicitor (for whatever that's worth!) so hoping she was on the ball when she came to the same conclusion.

I think I will give the whole thing a big think re permanent solution. I am also wondering if I just keep the existing structure, replace the decking boards myself like for like and try and figure out the railings as cheaply as possible. That said, I do like the idea of extremely low maintenance composite, just don't like the price.

Either way, think for now will get some OSB on the main decking area to spread any load and render it "safe" until spring!

Interesting devopments. That's a big drop for a domestic garden.

I'm not qualified to comment on Johnny's interesting contribution, but looks very helpful and it certainly shows the value of sharing technical problem on UKW.

As for 11mm OSB as a stopgap safety measure, I think it would be fine. People are often very disparaging about this material referring to it as "Weetabix". It is intended mainly for internal use but I have used it outdoors and it will lest well for at least a year in the open. Painting it all around with black bitumen paint will extend its life quite a bit and you may or may not prefer the appearance.

It would certainly be interesting to see how this project progresses.

Jim

 

[Molynoox]

Thanks for the suggestions, I definitely would love to avoid decking if I could but the decking is an overhang over a large drop ie would cost a lot to get anywhere near the structural support required for concrete paving.

Pictures below, I've got a quote in for £10,800 to complete remove all existing decking/frame etc and replace new treat frame and composite decking/fence panels.
The "basic" section is 3x6m and the other section of decking is 2x5m with another 6m of fencing required over the drop. I'm completely new to all this so have no idea how that quote looks (I'm up north for reference)

View attachment 166087View attachment 166088View attachment 166089

Nothing wrong with those prices for composite if they are doing it right.

The way I build decking, 70% of the labour is on the frame, 30% on fitting the boards. On material costs it's more like 80% boards 20% frame/foundations.

I would ask about the sub frame and foundations and see if they are building it right so it lasts as otherwise you are wasting your money. If the frame is good it will all last 30 years and will be a great investment.

The two main loaded questions:
-Material used for posts (if its timber then walk away - timber in the ground will rot)
-protection used for top of the frame work (if water can sit on the bare joists it will rot)

Martin

 

[mr rusty]

I think I would be inclined to go to a steel fabricator and get a steel frame/jetty made, and then just board myself.

 

[Mjward]

Interesting devopments. That's a big drop for a domestic garden.

I'm not qualified to comment on Johnny's interesting contribution, but looks very helpful and it certainly shows the value of sharing technical problem on UKW.

As for 11mm OSB as a stopgap safety measure, I think it would be fine. People are often very disparaging about this material referring to it as "Weetabix". It is intended mainly for internal use but I have used it outdoors and it will lest well for at least a year in the open. Painting it all around with black bitumen paint will extend its life quite a bit and you may or may not prefer the appearance.

It would certainly be interesting to see how this project progresses.

Jim

Thanks Jim, I like the idea of painting the OSB for extra protection. At the moment it's aesthetics are up again rotten wood decking with random broken boards so won't be that much of a downgrade and certainly not one I will worry about over winter

Nothing wrong with those prices for composite if they are doing it right.

The way I build decking, 70% of the labour is on the frame, 30% on fitting the boards. On material costs it's more like 80% boards 20% frame/foundations.

I would ask about the sub frame and foundations and see if they are building it right so it lasts as otherwise you are wasting your money. If the frame is good it will all last 30 years and will be a great investment.

The two main loaded questions:
-Material used for posts (if its timber then walk away - timber in the ground will rot)
-protection used for top of the frame work (if water can sit on the bare joists it will rot)

Martin

Totally agree Martin, I thought the (original) quote was fine. I did a rough calculation myself and this came out "only" 20% above that but given I've never done one before and just totting up various items I thought required, it was close enough to certainly seem fair. The key is what you say, if they are doing it right. Really like those 2 questions you pose and will reflect them. This is where I am generally very poor when interacting with tradesmen, I have this silly notion it's offensive to question a way things are done but I should have learnt by now it's a lot more offensive when they are done badly!

I think I would be inclined to go to a steel fabricator and get a steel frame/jetty made, and then just board myself.

I am certainly no expert in this field but I think the major stumbling block here would firstly be access. We live on an unadopted road that can't take large trucks and the access to the garden is via a narrow passageway with a 90 degree bend i.e. would only work if this fabricators could build on site. The second would be from a weight aspect. The smaller decking is over a sheer drop and currently supported by a few 45 degree braces into the retaining wall. The larger decking is over a smaller drop and built from the ground up, around 5m, and is just a wooden support structure.

 

[Mjward]

Nothing wrong with those prices for composite if they are doing it right.

The way I build decking, 70% of the labour is on the frame, 30% on fitting the boards. On material costs it's more like 80% boards 20% frame/foundations.

I would ask about the sub frame and foundations and see if they are building it right so it lasts as otherwise you are wasting your money. If the frame is good it will all last 30 years and will be a great investment.

The two main loaded questions:
-Material used for posts (if its timber then walk away - timber in the ground will rot)
-protection used for top of the frame work (if water can sit on the bare joists it will rot)

Martin

Sorry Martin, meant to ask before I clicked send: re the material used for posts, what is the right answer(s) here? Is it metal into the ground and above then the wood into this? Or even composite posts etc?

Re the protection, I've seen a few videos on this and a black waterproof tape seems to be very popular

 

[Molynoox]

Sorry Martin, meant to ask before I clicked send: re the material used for posts, what is the right answer(s) here? Is it metal into the ground and above then the wood into this? Or even composite posts etc?

Re the protection, I've seen a few videos on this and a black waterproof tape seems to be very popular

Hiya,

The two main options for posts are concrete (lintels or fence posts), and composite.

The frame should be bolted to the posts, not screwed.

The frame should, like you say, have either protective tape on top or strips of DPM/DPC. You could even paint the sides in barn paint or roof paint for double precaution but the main one by far is the tops that needs proper protection like the tape.

When speaking to them you don't want to lead the witness and suggest the right way, best to simply ask them how they will do it and go from there.

Martin

 

[Mjward]

Hiya,

The two main options for posts are concrete (lintels or fence posts), and composite.

The frame should be bolted to the posts, not screwed.

The frame should, like you say, have either protective tape on top or strips of DPM/DPC. You could even paint the sides in barn paint or roof paint for double precaution but the main one by far is the tops that needs proper protection like the tape.

When speaking to them you don't want to lead the witness and suggest the right way, best to simply ask them how they will do it and go from there.

Martin

How does this look Martin:

"The posts will be concreted into the ground with a quick set post mix, haunched above the ground height to stop water egress at ground height.
The framework is a pressure-treated 6x2" strength-graded C16. I haven't priced for decking tape, but it is rough £1.00 a l/m, and there is around 120m of framing."

Thanks for your help on this one, not something I'm familiar with at all

 

[davethebb]

You should perhaps consider the safety element a bit more (also a side note, did your surveyor pick up on the unsafe structure?). The decking looks like it can potentially have a relatively large number of people on it, this and the drop should be taken into account. I would consider using a steel frame that can be bolted/welded etc. with a wooden deck on top. This is likely to be cost-effective as most of it can be fabricated off-site.

 

[Molynoox]

How does this look Martin:

"The posts will be concreted into the ground with a quick set post mix, haunched above the ground height to stop water egress at ground height.
The framework is a pressure-treated 6x2" strength-graded C16. I haven't priced for decking tape, but it is rough £1.00 a l/m, and there is around 120m of framing."

Thanks for your help on this one, not something I'm familiar with at all

It's not a great response from them. An expensive deck like that needs to last and I wouldn't be using wooden posts into the ground, even if they haunch it it will still decay.

Same goes for the tape, I can't believe they were planning on leaving it unprotected. You as a customer shouldn't need to be doing these sort of quality checks IMO.

Martin

 

[Mjward]

You should perhaps consider the safety element a bit more (also a side note, did your surveyor pick up on the unsafe structure?). The decking looks like it can potentially have a relatively large number of people on it, this and the drop should be taken into account. I would consider using a steel frame that can be bolted/welded etc. with a wooden deck on top. This is likely to be cost-effective as most of it can be fabricated off-site.

After learning that planning permission is required for decking over 30cm off the ground I did have a small panic as the previous owners so far haven't proved great at that type of stuff but have gone through the council website and see the current decking structure got signed off from both a planning permission perspective and building control perspective so I'm happy from a safety angle, have seen many built in a similar way. The (only) problem I have with a steel frame is access, not only am I very rural (large trucks can't get to the house) but once at the property the only way to the garden is via a dog-leg staircase i.e. no way to get anything large & heavy down it.

It's not a great response from them. An expensive deck like that needs to last and I wouldn't be using wooden posts into the ground, even if they haunch it it will still decay.

Same goes for the tape, I can't believe they were planning on leaving it unprotected. You as a customer shouldn't need to be doing these sort of quality checks IMO.

Martin

I am getting a similar feeling. Had googled the post mix etc and it seems very common to get rot where the timber is just visible above the concrete i.e. maybe not as bad as if the timber was directly in the soil but only marginally better. As you say having it bolted onto set concrete above ground height seems the higher quality/longer lasting approach. As for the tape/protection, the price quoted to do it is fine but I'm erring to your point on this, for that price it should be a high standard at every aspect by default and now opens my mind to concerns about other cost-cutting measures that I haven't enquired about.

In the past week I've been hit with roofing costs (leak) and plumbing costs so will put this project on hold. For now will OSB sheet where we are likely to stand between now and spring and will re-assess. Part of me is hoping the existing frame/structure is in decent condition (it's 10 years old) and in spring I might just have a go at replacing the boards and railings myself if that is the case. I'm doing carpentry/joinery every day so seems a bit crazy to pay for that element, I was only outsourcing the whole project as not keen on heights i.e. replacing the whole structure.

 

[MikeJhn]

Have not read the whole post, but if supporting horizontal timbers on a vertical post I would not rely on bolts or screws to support the beams/joists, but support them on the top of the posts or even at a pinch joist hangers so the joint is in compression.

 

[Mjward]

Have not read the whole post, but if supporting horizontal timbers on a vertical post I would not rely on bolts or screws to support the beams/joists, but support them on the top of the posts or even at a pinch joist hangers so the joint is in compression.

Have had to park the plan for now but it gives me time to learn a lot more about the right way to do it so thank you!

 

[MikeJhn]

Increasing the photo's somewhat it looks as though the decking is supported on raking shores off the wall supporting the paved area, is this correct, if so what are they?

How far is it to the ground level below the decking?