# floor joists and plumbing



## Richard S (6 Aug 2011)

Hi Guys
Not sure this is the correct place for this but here goes; 

We currently have a shower in the bathroom that has been raised to allow the drain to be boxed in above the floor, which has been fine up until now. We are now in a situation where I need to lower the tray down to floor level to make access easier for my wife. The problem is, doing this means the drain will be below floor level and will have to run perpendicular to the joists. I think the drain is 32mm which seems a big chunk to notch out of a 200mm joist. does anyone have any experience or knowledge of shower installation or plumbing practices in general.

Any and all advice gratefully received.

Many Thanks

Richard


----------



## Tusses (6 Aug 2011)

I dont know the spec for notching joists, but on a boat, you would pump the shower/sink waste out. 
It would solve your problem and it's quite cheap.

Just an idea if nothing else comes up


----------



## Cowboy _Builder (6 Aug 2011)

I've sent a PM ... Allan


----------



## Mcluma (6 Aug 2011)

I have seen this product called dry deck. this also pumps out wast, but uses 22mm pipe and the pump action is dependend on the flow of the pipes of the shower, they fit flow sensors on the hot and cold pipe, and the more water you use, the more it will pump - clever


----------



## Lons (7 Aug 2011)

Hi Richard

I personally wouldn't be notching the joists much if at all though it depends as much on the span as the depth of the joists.

It 's highly unlikely your pipework is 32mm as a standard shower waste is 40mm and then you also have to allow additional depth for fall.

Apart from the pumped solutions which might be your only option, you can these days buy very shallow trays and waste outlets which might allow an acceptable compromise. You do have to be carefull to ensure that water will always drain away faster than the shower output of course or you'll have an unwelcome flood.

Bob


----------



## devonwoody (7 Aug 2011)

I have been looking into a similar problem lately and I need to box the outlet pipe above floor level also.

My solution is going along these lines, a shower cubicle that has a side entry (definately not a central entry) so that a handrail can be fitted at outside to a wall at entry and another internally. 

Mira have a shower cubicle as per drawing and is the only one I have come across of the quadrant type. Mira flight is the model.


----------



## Deejay (7 Aug 2011)

Morning Richard

There is some information about drilling / notching joists here ...

http://www.carryduffdesigns.co.uk/techn ... oists.html

Mcluma

Thanks for the dry deck suggestion. Might be what I need for a shower installation at our daughter's house.

Cheers

Dave


----------



## Eric The Viking (7 Aug 2011)

@Richard S:

You don't say how old the house is or what sort of building. Generally speaking, the inter-floor space and the joist thicknesses are larger in older houses (up to a point - cottages tend to be an exception!). 

But you're right: it's a really bad idea to make big notches. Can you run the pipe parallel to the joists and through an outside wall? It would be much stronger/safer, as long as the outside bit won't freeze in winter. 

Showers should be 40mm waste, not because of water flow on its own, but because they tend to block with hair, etc and the flow gets restricted that way. 40mm is the O.D., but in practice, that still means a 42mm or 45mm hole in anything the pipe needs to pass through (available drill sizes and room for alignment errors/wiggling, etc.) - not a very good idea. 

You might drill through the middle of tall, lightly loaded and good condition joists, and you can coach-bolt wood either side to strengthen them (use spiky washers between), but there is still the fall to consider, as mentioned. Bathroom joists aren't heavily loaded, except the ones that carry the bath itself! Whilst central through-holes are OK (-ish) there is another practical consideration: getting the pipe in there in lengths longer than the space between joists -- unless there is an opening to the outside at the end of the run, it isn't possible to do it in one piece, and joints mean greater possibility of leaks and blockages. 

I'm never tempted by push-fit unless it's truly unavoidable. Glued (solvent-weld) joints are pretty much as strong as the pipe itself, and, if you clean burr from the inside of the pipe carefully, don't tend to catch debris as much as sawn polythene push-fit. 

You've also got two 'nuclear' options: (1) raise all or part of the bathroom floor a bit. You'll gain the raise plus the existing floorboard thickness, and you won't compromise the structural integrity. (2) completely re-work the bathroom with a different layout - may not solve the problem though!

My favourite would be a new route for the waste pipe (parallel to the joists).

E.

PS: Just a word to the wise - don't be tempted to join your 40mm pipe into the side of a horizontally-running soil pipe (if you have one). It should enter from the top. There are also these things: 


 
that might make things tidier on an inside stack (vertical pipe), although they tend to be used in new-build, as they need a bit of space.


----------



## jasonB (7 Aug 2011)

Whats under the bathroom, another option would be to run the waste under the ceiling joists and have a small boxing ideally along the top of a wall rather than across the middle of a ceiling. Its not the nicest solution but it is practical.

You can drill in the neutral section of the joist near a wall but all the points Eric said apply.

A sanishower pump could also be used, these are small enough to fit within the joist depth and will enable you to pump the water through 22mm pipework. You do need access but they can be sited in anadjacent room under a access panel

How much can the person step over? Old trays tend to be 4-6" high, a modern tray may only be about 30mm, this can still be raised enough for the trap and fall without having to step up very high.

J


----------



## bosshogg (7 Aug 2011)

Richard, I have had ramps installed to showers in the past for just this problem, they must comply with the current regs which is 1:8 minimum current, but advisory 1:12 to be more user friendlily...worth a thought!
If however you want to go down the recessing of the shower tray/floor, how many perpendicular joists do you need to traverse?


----------



## Eric The Viking (7 Aug 2011)

jasonB":d7wjqs2h said:


> Whats under the bathroom, another option would be to run the waste under the ceiling joists and have a small boxing ideally along the top of a wall rather than across the middle of a ceiling. Its not the nicest solution but it is practical.



That's a good solution, too.

We're lucky enough to have three WC+bathrooms roughly in vertical line with each other. The bottom two have false (lowered) ceilings. The middle room has quite a lot of stuff going through the void: extractor ducting, cabling, and the 40mm bath and shower wastes above, into a horizontally-running 110mm soil pipe for the loo at the top. 

Having a lower ceiling makes it quite a bit warmer in the winter, too, and I don't think you'd realise ours were unless you were looking for it.

E.


----------



## studders (7 Aug 2011)

I had to go through 3 joists and then out the wall when I put our shower in. I drilled through the center part of the joists and staggered the holes so I could get shorter lengths of waste in. Fortunately I had quite sizeable joists so drilling near the center was OK. The hardest bit was lining up the hole in the wall with the hole in the last joist.


----------



## devonwoody (8 Aug 2011)

I suppose you should do the hole outside first?


----------



## studders (8 Aug 2011)

devonwoody":2zm40ycj said:


> I suppose you should do the hole outside first?


It crossed my mind DW but at the time it seemed it would be just as much 'guess n hope'.


----------



## Richard S (15 Aug 2011)

Thank you to everyone who replied to this post, sorry it has taken me so long to register my appreciation but I've done nothing but work for the last week or so, I've now got a few days off and will be able to condider these responses in more detail. By far the easiest option would be Jason idea of coming straight through the floor and ceiling below and have a short run along the top of the kitchen wall which can be boxed in. The down side to this is my analy retentive attitude to non-concealed services, but as the medium term plan is to turn the current kitchen into a utility room I may just have to live with this. Thanks once again to you all.

Richard


----------



## DaveyP (15 Aug 2011)

Anything is possible if you throw enough money at it...

But for every problem there is normally a simple solution, have a look at

http://www.rdkmobility.co.uk/Adjustable-Bath-Step.html


----------



## bosshogg (15 Aug 2011)

Earlier I asked how many joists you would have to traverse, I asked because a simple solution would be to bridle the joists in question, I am a construction Project Manager, and could talk you through the processes if you like?...bosshogg


----------



## markturner (15 Aug 2011)

You could also remove sections of joist to give the clearance and replace with trimmers and or doubled up sections to provide open area to run the pipe in. In the same way you would form an opening in a floor for a staircase, but smaller....

PS< the pumped waste solutions are great, but are not cheap, at approx £1000 and are a complex install. We use them a fair bit doing wetrooms.

Cheers, Mark


----------



## Richard S (15 Aug 2011)

Hi Bosshogg

Thanks for your input, until I lift the floor I don't know how many joists, if they are standard 450 centres I would estimate between 4 and 6 depending on the location of the drain in the shower tray. What do you mean by bridling the joints? Thanks once again.

Hi Mark

Thanks for your input also, by trimmers do you mean noggins like in a vertcal wall application?

I'm going to lift part of the floor hopefully later this week to see what lurks below.

Richard


----------



## bosshogg (15 Aug 2011)

Hi Richard, bridling joists means cutting them and nailing the same dimension of timbers to straddle the cuts, thereby if the original joists were cut to produce a 300mm slot over, let's say five joists. and the bridling timber was the length between seven joists, you could effectively transfer the load too the two outermost joists.



Obviously* this is a simplistic explanation*, extra strengthening would be required dwangs/noggins would be installed to beef up the slotted void etc.
Alternatively steel plating could be affixed too support the cut joists, it all depends on what depth of cuts you would have to make.
Have a look at these, try visualising your likely needs 


and let me know what and iff you want too go ahead...bosshogg  

Edit: Mark may be talking the same thing, it's just semantics.



> The important thing is not to stop questioning.
> Albert Einstein (hammer)


----------

