Hi All,

I have a question about pressure-treated decking joists:

Our house has a decked cantilever balcony around 2 sides on the 1st
floor, where the balcony joists protrude about 1 metre from the outside
wall, and go right through the cavity wall and bolt to the floor joists
on the inside. (Hope you can understand this description!)

Anyway, it's all rotten and I have now removed most of the old joists,
leaving just slots in the brickwork ready to accept some new joists.
Obviously I want to replace with pressure treated decking joists, as I
don't fancy doing this job again for a while! However, I'm having
problems sourcing joists that will fit into my existing slots...

I've determined that the joist sizes I need are 2.4m long, 43mm thick,
and 170mm tall, i.e. not a standard size. (This is about 1 or 2 mm
undersized so I can be sure they'll fit - don't know whether I need to
take shrinkage/expansion into account here?)
However ringing round the local timber merchants, one has said that you
can't plane pressure treated joists as you'll lose the weather
resistance, and one has said they can saw it but not plane it (for the
same reason)!!??

Now some things I've read tell me the pressure treatment penetrates
right to the middle of the wood, but is this the case? Is it a waste of
time to plane pressure treated joists? Surely sawing would give the same
problem if it is an issue?

Thanks,
Ben.

Ben Willcox wrote:
Our house has a decked cantilever balcony around 2 sides on the 1st
floor, where the balcony joists protrude about 1 metre from the outside
wall, and go right through the cavity wall and bolt to the floor joists
on the inside. (Hope you can understand this description!)

Anyway, it's all rotten and I have now removed most of the old joists,
leaving just slots in the brickwork ready to accept some new joists.

I've determined that the joist sizes I need are 2.4m long, 43mm thick,
and 170mm tall, i.e. not a standard size. (This is about 1 or 2 mm
undersized so I can be sure they'll fit - don't know whether I need to
take shrinkage/expansion into account here?)
However ringing round the local timber merchants, one has said that you
can't plane pressure treated joists as you'll lose the weather
resistance, and one has said they can saw it but not plane it (for the
same reason)!!??

Now some things I've read tell me the pressure treatment penetrates
right to the middle of the wood, but is this the case? Is it a waste of
time to plane pressure treated joists? Surely sawing would give the same
problem if it is an issue?

Pressure treatment goes in a few mm, but there is definitely more at
the surface than in the middle. The only reason I can think of that
the timber merchant thinks they can saw it, is that they plan to paint
something on the sawn surface - and you can get more liquid to stick to
a sawn surface than a planed one.

Why not make the holes a bit bigger? Lots of people here rave about
SDS drills (I've never used one). It sounds like the sort of thing a
chisel attachment ought to make short(ish) work of.

Ben Willcox wrote:

I've determined that the joist sizes I need are 2.4m long, 43mm thick,
and 170mm tall, i.e. not a standard size. (This is about 1 or 2 mm
undersized so I can be sure they'll fit - don't know whether I need to
take shrinkage/expansion into account here?)
However ringing round the local timber merchants, one has said that you
can't plane pressure treated joists as you'll lose the weather
resistance, and one has said they can saw it but not plane it (for the
same reason)!!??

Go to Jewsons and get them to cut the timber to whatever size you want
and treat it for you.

wrote:

Pressure treatment goes in a few mm, but there is definitely more at
the surface than in the middle. The only reason I can think of that
the timber merchant thinks they can saw it, is that they plan to paint
something on the sawn surface - and you can get more liquid to stick to
a sawn surface than a planed one.

Why not make the holes a bit bigger? Lots of people here rave about
SDS drills (I've never used one). It sounds like the sort of thing a
chisel attachment ought to make short(ish) work of.

Hi Martin, thanks for the reply.

You know, I'd never actually thought about enlarging the holes... I had
totally discounted it as I figured enlarging 45 holes in 2 layers of
brick wall would be out of the question. However now you suggested it,
I've looked and 150mm x 47mm joists are a common size, so I'd only
actually have to enlarge the width by 4mm (which is mortar anyway) so
might not be too hard.
I hope the reduction on the vertical by 20mm wouldn't matter much
strength wise (I think the joist spacing is about 16 inches but thats
guessing from memory...)?

Cheers,
Ben.

On Wed, 01 Jun 2005 12:47:57 +0100, Ben Willcox
wrote:

I have a question about pressure-treated decking joists:

Don't use them - they're not weatherproof. If you want them to last, a
timber that's inherently rot-resistant (larch or oak, depending on
budget) will last far longer than crapwood doused in poisons.

On Wed, 01 Jun 2005 12:47:57 +0100, Ben Willcox
wrote:

Hi All,

I have a question about pressure-treated decking joists:

Our house has a decked cantilever balcony around 2 sides on the 1st
floor, where the balcony joists protrude about 1 metre from the outside
wall, and go right through the cavity wall and bolt to the floor joists
on the inside. (Hope you can understand this description!)

Anyway, it's all rotten and I have now removed most of the old joists,
leaving just slots in the brickwork ready to accept some new joists.
Obviously I want to replace with pressure treated decking joists, as I
don't fancy doing this job again for a while! However, I'm having
problems sourcing joists that will fit into my existing slots...

I've determined that the joist sizes I need are 2.4m long, 43mm thick,
and 170mm tall, i.e. not a standard size. (This is about 1 or 2 mm
undersized so I can be sure they'll fit - don't know whether I need to
take shrinkage/expansion into account here?)
However ringing round the local timber merchants, one has said that you
can't plane pressure treated joists as you'll lose the weather
resistance, and one has said they can saw it but not plane it (for the
same reason)!!??

Now some things I've read tell me the pressure treatment penetrates
right to the middle of the wood, but is this the case? Is it a waste of
time to plane pressure treated joists? Surely sawing would give the same
problem if it is an issue?

Thanks,
Ben.

Hi,

Sounds like you need to speak to a good sawmill with pressure treating
facilities, or a very good timber merchant who can order special sizes
and arrange for pressure treating.

One way go would be to get strength/stress graded timber graded for
wet conditions, sawn to spec, and pressure treated with a copper based
preservative.

A structural engineer with the right experience would be able to
calculate the safe loading on the balcony.

Normal decking joists aren't strength graded, may be made of poor
timber that will warp/twist, and the preservative may only be a wax
based water repellent.

See also:

http://www.google.co.uk/search?hl=en&q=site%3A.uk+strength%20graded%20timb er&btnG=Search
http://www.google.co.uk/search?hl=en&q=site%3A.uk+wood%20pressure%20treatm ent&btnG=Search

Depending on the rest of the balcony and it's design, if you're lucky
you may be able to get oak at a competitive price, though it's not
normally strength graded.

cheers,
Pete.

On Wed, 01 Jun 2005 12:47:57 +0100, Ben Willcox
wrote:

Hi All,

I have a question about pressure-treated decking joists:

Our house has a decked cantilever balcony around 2 sides on the 1st
floor, where the balcony joists protrude about 1 metre from the outside
wall, and go right through the cavity wall and bolt to the floor joists
on the inside. (Hope you can understand this description!)

Anyway, it's all rotten and I have now removed most of the old joists,
leaving just slots in the brickwork ready to accept some new joists.
Obviously I want to replace with pressure treated decking joists, as I
don't fancy doing this job again for a while! However, I'm having
problems sourcing joists that will fit into my existing slots...

I've determined that the joist sizes I need are 2.4m long, 43mm thick,
and 170mm tall, i.e. not a standard size. (This is about 1 or 2 mm
undersized so I can be sure they'll fit - don't know whether I need to
take shrinkage/expansion into account here?)
However ringing round the local timber merchants, one has said that you
can't plane pressure treated joists as you'll lose the weather
resistance, and one has said they can saw it but not plane it (for the
same reason)!!??

Now some things I've read tell me the pressure treatment penetrates
right to the middle of the wood, but is this the case? Is it a waste of
time to plane pressure treated joists? Surely sawing would give the same
problem if it is an issue?

Thanks,
Ben.

Clifford Jones timber in Ruthin will almost certanly be able to supply
your need, however you may have a shock at the price, even though it
will be the cheepest of 2 or 3 I could recommend.



Rick

Rick wrote:
Clifford Jones timber in Ruthin will almost certanly be able to supply
your need, however you may have a shock at the price, even though it
will be the cheepest of 2 or 3 I could recommend.

Hi guys, thanks for all the responses. As Chris suggested I called my
local Jewsons, and they said they could cut to size and send it off to
be pressure treated (none of the other local merchants I rang would do
this).

They quoted me 325 quid inc VAT for 46 off 2.4m x 43mm x 170mm, with a
taper cut at one end to match the originals. (works out around 2.50 per
metre)

Dunno whether this is a good price or not...?! I'm guessing oak would
cost me a little more than that!

Rick thanks for the recommendation however I think delivery costs would
be prohibitive so would be better to try and get it as local as I can
(I'm in Telford, Shropshire).

Cheers,
Ben.

On Wed, 01 Jun 2005 19:55:41 +0100, Ben Willcox
wrote:

Dunno whether this is a good price or not...?! I'm guessing oak would
cost me a little more than that!

Phone and find out
http://www.bendreybrothers.co.uk

"Ben Willcox" wrote in message
...
Hi All,

I have a question about pressure-treated decking joists:

Our house has a decked cantilever balcony around 2 sides on the 1st
floor, where the balcony joists protrude about 1 metre from the outside
wall, and go right through the cavity wall and bolt to the floor joists
on the inside. (Hope you can understand this description!)

Anyway, it's all rotten and I have now removed most of the old joists,
leaving just slots in the brickwork ready to accept some new joists.
Obviously I want to replace with pressure treated decking joists, as I
don't fancy doing this job again for a while! However, I'm having
problems sourcing joists that will fit into my existing slots...

I've determined that the joist sizes I need are 2.4m long, 43mm thick,
and 170mm tall, i.e. not a standard size. (This is about 1 or 2 mm
undersized so I can be sure they'll fit - don't know whether I need to
take shrinkage/expansion into account here?)
However ringing round the local timber merchants, one has said that you
can't plane pressure treated joists as you'll lose the weather
resistance, and one has said they can saw it but not plane it (for the
same reason)!!??


Find a decent timber merchant and ask them to cut standard untreated C16
wood to the correct size then have it tannelised. If they don't have the
equipment then their supplier will.

In message , Ben Willcox
writes
They quoted me 325 quid inc VAT for 46 off 2.4m x 43mm x 170mm, with a
taper cut at one end to match the originals. (works out around 2.50 per
metre)

Dunno whether this is a good price or not...?!

I'd snap their hand off at that. I reckon that's only slightly above the
going rate for 50x170, and given the amount of work its going to save
you....no brainer as they say.


--
steve

On Wed, 01 Jun 2005 19:55:41 +0100, Ben Willcox
wrote:

Rick wrote:
Clifford Jones timber in Ruthin will almost certanly be able to supply
your need, however you may have a shock at the price, even though it
will be the cheepest of 2 or 3 I could recommend.

Hi guys, thanks for all the responses. As Chris suggested I called my
local Jewsons, and they said they could cut to size and send it off to
be pressure treated (none of the other local merchants I rang would do
this).

They quoted me 325 quid inc VAT for 46 off 2.4m x 43mm x 170mm, with a
taper cut at one end to match the originals. (works out around 2.50 per
metre)

Dunno whether this is a good price or not...?! I'm guessing oak would
cost me a little more than that!

Rick thanks for the recommendation however I think delivery costs would
be prohibitive so would be better to try and get it as local as I can
(I'm in Telford, Shropshire).

Cheers,
Ben.

Thats 12 quid a cubic foot, you would have to pay a couple of quid
more for oak, but not much, and then you would have the good old
transport problem back :-(

Rick