# Forum Home Renovation Waterproofing  Quick bond breaker questions

## johnnt

Hi all, 
A couple of quick bond breaker questions which i've not managed to find answers too :  
I am about to waterproof a shower which has an 80mm recess into the concrete slab. My plan is to waterproof the recess which is part of the slab, then install the villaboard and screed then waterproof over the top and of course, fit bond breakers at the joints where the screed meets the villaboard (and internal wall corners as usual). 
Is it ok to not install bond breakers in the recessed slab as it is a single piece of concrete and the base cannot move seperately from the sides? 
Second question,  i am having to install the villaboard horizontally due to the size of the shower, do i need to do anything special where the joint is from a waterproofing perspective, or if i tape and coat the joint as normal is it treated as a single sheet and just waterproofed? 
Thanks 
J

----------


## Skinah

If you waterproof on top of the screed you must wait for it to be fully dry AFTER correctly curing the screed first. Curing means keeping the screed damp. So it may mean delaying the job 20+ days depending on how thick the screed is. 
If you install the sheeting, water proof and then install the screed you can get on to tiling quicker if you choose to not water proof on top. 
First question, not sure but I would as you can use silicon in a 12mm bead as a bond breaker and then use normal bandage on top of silicon. If you sheet first you can do it all at the same time. Don't forget some wood in the areas you water to screw the glass to, wood for towel rails, toilet roll holder and hand rails for elderly that kind of thing before you sheet. 
This link may be of interest   https://www.renovateforum.com/f205/s...nsuite-119419/

----------


## johnnt

Thanks Skinah, nice shower ! 
At this stage i have decided to just WP below the screed and depending on how the next few days go I will review this decision. 
I have sheeted the two walls of the recess (which extends down into the recess 75mm) and used 11fc for all joints. Got a little carried away with the jointing beed but as i'm going to be using the fabric with built in bond breaker so i guess a little extra filling shouldn't matter too much. 
i'm still interested to understand whether a taped and filled horizontal board joint is considered two different surfaces which could move independently and therefore need a bond breaker. I was planning on reinforcing the joints with wp fabric but not the one with built in bond breaker. 
Cheers 
J

----------


## phild01

Running your boards horizontal is fine, just don't topcoat the joins, no need for bond breaking.  Also backblock the joins.  Waterproofing the walls is way over-rated compared to the floor to wall requirement.  I have pulled old showers apart with no wall waterproofing and with nil wall water damage.  You need to waterproof the walls though, but just be sure the floor area and wall intersections are given close attention to bond breaking and manufacturer's application. 
A good guide to waterproofing thickness is to read what the manufacturer says about coverage.  If you think you have applied enough but find you have used less than what is spec'd, then keep going with further coats.

----------


## johnnt

> Running your boards horizontal is fine, just don't topcoat the joins, no need for bond breaking.  Also backblock the joins.  Waterproofing the walls is way over-rated compared to the floor to wall requirement.  I have pulled old showers apart with no wall waterproofing and with nil wall water damage.  You need to waterproof the walls though, but just be sure the floor area and wall intersections are given close attention to bond breaking and manufacturer's application. 
> A good guide to waterproofing thickness is to read what the manufacturer says about coverage.  If you think you have applied enough but find you have used less than what is spec'd, then keep going with further coats.

  
Thanks Phil, 
I've done waterproofing before using the same kit so i'm not too worried about getting the right coverage, I will probably do more than less - it was just more that last time the shower was small enough to use vertical boards without a join. In my mind the boards can in theory move independently at the join however probably not enough to be of consequence. The studs are 350 apart as well so quite a bit of support. 
J

----------


## phild01

Backblocking is easy and the boards won't move.  Villaboard joins must be supported by either noggins or backblocking.

----------


## johnnt

> Backblocking is easy and the boards won't move.   Villaboard joins must be supported by either noggins or  backblocking.

  hmm, i've not back blocked or used noggins  as per the villaboard installation manual which says it's not mandatory.  i've taped and filled the joints and there doesn't seem to be any  movement. i will have to see how it goes as there's not opportunity to  back block at this stage. 
the shower recess is pretty small with  studs at 350. two walls are villaboarded horizontally with a joint at  350 high on one side and 1200 high on the other. i didn't want the joint  to be inline with the mixer valve so i used the short board on that  wall hence the 350. 
J

----------


## phild01

> hmm, i've not back blocked or used noggins  as per the villaboard installation manual which says it's not mandatory.  i've taped and filled the joints and there doesn't seem to be any  movement. i will have to see how it goes as there's not opportunity to  back block at this stage.

  Been a while since I referred to their installation manual but I do remember it being in-line noggins for the boards join.
refer note 2 page 9 of their recent publication. http://www.jameshardie.com.au/upload...20OCT%2014.pdf 
I wouldn't deviate from that recommendation.

----------


## johnnt

> Been a while since I referred to their installation manual but I do remember it being in-line noggins for the boards join.
> refer note 2 page 9 of their recent publication. http://www.jameshardie.com.au/upload...20OCT%2014.pdf 
> I wouldn't deviate from that recommendation.

  Yes i saw that, and the combination of "although not mandatory" in note 2 and the recommendation for noggins only for "high impact" areas in note 3 suggested a low impact area so not needed. 
I guess it's too late now - i've taped the joins and also reinforced them during the WP with a membrane with built in bond breaker. It all feels very solid. Also studs are closer that than the 600max so hopefully should be ok. 
J

----------


## phild01

10mm thick tiles with a cement based adhesive will hold it all quite well.

----------

