The subject of weep holes on tile roofs can get quite ‘touchy’.
Weep holes or no weep holes?
This is a subject of much debate amongst roof tilers in Sydney (and the rest of Australia – it seems).
Why do we need weep holes?
Well, the picture on the left shows what happens when no weep holes are installed in the bedding along a ridge – and the bedding is cracked under the ridge.
Initially, the crack in the bedding under the capping will allow water to seep through and collect on the scalloped zone of the roof tile upstream of the bedding. When the bedding is firmly stuck to the roof tile and also if there are no weep holes, the ponded water grows in size as more water seeps in. Eventually, the pond overflows the top edge of the roof tile and into the roof cavity.
This usually takes a while to happen and that is why leaks at the ridge capping only happens during prolonged rainfall.
The combination of the two (cracking under the ridge cap and a watertight seal of the bedding to the top of the roof tile) can cause a roof leak under the capping.
It is important to note here that if you have one and not the other, there will be no roof leaks at the capping. This is why some painted roofs start to leak when they did not leak prior to painting. Prior to roof painting, the bedding may not be fully adhered to the roof tile and this allowed a seepage path for the built up water. Roof paints can be quite thick and will seal any cracks between the bedding and the roof tiles. Suddenly, both conditions are met and a leak appears…
In the past, the pointing work was done with an oxide coloured sand/cement mortar. Roofers back then knew that the pointing was quite like to crack under the ridge capping and let water in. That is why they were quite diligent in installing weep holes to prevent any leaks. Then Flexible pointing was introduced.
And because flexible pointing stuck to the ridge capping so well and did not crack (as much), roofers start to think that they could do away with weep holing all together. And they were mostly right. If there is no cracking of the pointing – then there will be no water build up and hence no need for any weep holes… So, the no weep hole (old fashioned) myth about flexible pointing started to spread.
But there is one thing wrong with this myth. It assumes that the flexible pointing will maintain its integrity and not crack. Unfortunately, there are some instances where flexible pointing will fail. The two most obvious are: excessive movement at the ridge capping/roof tiles, and application error by the roofer. This is why the flexible pointing manufacturers still insist that weep holes be installed through their material. It is a safety margin thing.
Are there any exceptions?
Well, of course there is.
- Terracotta roof tiles have a border system at the top of the tile that acts as a dam wall against any ponding that can build up. So, if a full tile is installed on the top row under the ridge capping, weep holes cannot be installed and they are not needed. However if a cut tile is on the top row, then weep holes are still needed.
- With the recent fashion of using flat profile concrete roof tiles, weep holing can be a bit of an option. This is because there are no scallops in the roof tile to collect the water. Any seepage will pool horizontally behind the bedding, run to the lap of the tile and dribble into the drainage course underneath. The drainage course acts as a alternative weep hole! But this doesn’t stop roofers from putting weep holes in anyway…
- When a ridge cap is repointed and the old bedding is quite sound and has no weep holes installed. This is a debatable case. Either the ridge capping is removed ( probably a more expensive exercise) or the ridge capping is repointed carefully (cheaper option). If the old bedding is sound – then there is very little likelihood of movement cracking in the new flexible pointing and if the pointing is put on carefully (with the right preparation), chances are that there will be no cracking of the flexible pointing. In this case, I leave the decision to the homeowner whether to weep hole or not. I will guarantee both options.
Every now and then I am asked if weep holes can be drilled into the bedding when all the pointing has been done and set. The answer is NO. I just don’t think that this can be done effectively. Weep holing has to be performed before the bedding sets. Then after the pointing is done, the weep holes have to be re-established through the fresh pointing.
I also posted a blog on ridge cap repairs
I have a video there that goes through a roof leak that was caused by cracks under the ridge capping but no weep holes in the bedding. And what we did to fix it.
Check it out below if you want to see what weep holing us all about…
[comment comment_file =”/comments.php”]
video was great but the music is louder than the commentry
Dave,
Thanks for the feedback.
I guess we are better at roof repair work than video compilations.
I will tone down the music levels and concentrate on the audio on my next set of roofing videos.
Jack
Thanks Jack very educational. I learned lots. cheers. Tony
Thanks Tony,
There is more roofing repair content to be uploaded to this website – when I can find the time to do it. Glad you found what is already here to be helpful.
Jack Yuen
Are weep holes a Australian standard or requirement??
Thanks
Hi John,
I am not sure about weep holes in any Australian standard.
But I do know that weep holes can make the difference between a leaking ridge or a waterproof one – once there is a crack in the pointing at the edge of the ridge cap.
It is just a good insurance against future leaks due to deterioration of the pointing (which is bound to happen)…
Hope this helps.
Jack
Thanks for the video. We have been trying to work out what is meant by weep holes in ridge capping after an insurance claim. So this illustrated it very clearly. Looks like we will have to have our roof re pointed. Now that I understand what they were trying to explain to us. Thanks
Hi There , glad to finally see some info on weepholes on the net . People always wonder what your doing drilling holes in there roof to fix a leak and Im sure some don’t believe a word you say when you try to explain it . One thing you are wrong about though is that you say it only leaks when the pointing starts to crack , this is totally untrue . A brand new roof with no cracks will leak if one is missed or is blocked after some continuous rain . Cracking will certainly make it worse but cracks or no cracks it will definitely leak . That aside your explanation is really good and will be handy for people to read .
Cheers
My roof leaks and nothing obvious.
But it seems to leak on the side of the roof where there are weep holes. The other half that has been redone (by previous owner) doesn’t show any signs of leaking. This all one continuous ridge line.
Scratching my head.
Hi John,
You are not the only one to resort to head scratching… I do that quite often because roof leaks can be quite hard to track down.
I think in your case, it may be weep holes that are blocked or you have a tile with a damaged water course (which you cannot see until you lift up the adjacent tile).
Hope this helps.
Jack
My problem is that my terracotta tiles which were painted 20 years back are getting holes in them. So far there are only a few which I have replaced. When the tiles are taken down there is disintegration on the underside. I don’t want to replace my roof so is my best option to keep on replacing tiles as the develop holes.
Hi Barbara,
Looks like you have ‘fretting’ terracotta roof tiles. There is nothing that you can do to slow down the rate of deterioration when your tiles start fretting.
If you do not have sarking under the tiles, the best way is to get into your ceiling cavity to spot the worst offenders and get these replaced. If the roof is sarked, it is a bit harder. This means you have to get on the roof and randomly lift tiles out to find the worse tiles.
Just keep replacing the really bad ones and you will be able to extend the life of the roof for quite a few years.
All the best,
Jack
Can you please tell me how deep should I drill for concrete ridges and what diameter the bit should be. Thanks very much
Hi Rohan,
I have never successfully drilled weep holes. The depth depends on how thick the bedding is. The drill hole has to fully penetrate the bedding. It only has to be about a 5mm diameter hole. Be careful not to drill through the tile.
My recommendation is to remove the ridge capping and start again with fresh bedding.
Jack
hi
I am Hadny man and I was repair leaking from craks of the ridge capping . so I did make cement bedding and along the ridge capping without weep holes and there has no leaking any more even prolonged period of rain .There has no weep holes existing condition so I just repair for cracks by cement 7 month ago as common mathod. I gave 1year waranty to customer, stiil 5 month left for warranty .
but now, the customer claim to me making a fresh weep holes due to wrong way i did
I don’t understand this situation. do I have to do for free? could you please give your opinion
Hi John,
A lot depends on your contract with the homeowner.
If it is just to repair a leak with a certain warranty, and if your repair work is still effective – then you have carried out your part of the contract and the home owner should not ask you more than what you have said you would do ie. ‘just fixing the leak – for 12 months’.
We have a 7 year warranty on our work. And we know that we need to put in weep holes (in most main ridging situations) so that we do not get a leak during that long time frame. This is because the bedding/pointing to the capping has a good chance of developing cracks in that time period – and causing leaks again.
Hope this helps.
Jack
Hi,Jack
Thank you !
Hi, Jack
Could you please explain how to drill weep holes in ridge capping around? If there were no weep holes
Thnks
Hi John,
Drilling weep holes is not 100% effective.
If the cut tiles are too short and/or the bedding is too thick, there is no clear tile surface for water to collect and drain through the weep holes.
The only way to tell is to take the ridge capping off.
However, If you have done the bedding yourself and know that the tiles are long enough and the top edge protrudes past the bedding, then you can use a 300mm long x 5mm diameter masonry drill bit (on screw function rather than hammer) and drill the weep holes carefully.
Hey Jack
Quick question, I have a cement tile roof; I have recently just jumped on the roof to have a look as it looked like a tile was broken. When I was up there on multiple tiles there was a small hole going into the tile (which didn’t go through the other side). Is there anything I can get to fix this ?
Hi Patrick,
I think you are referring to the nail hole locations on the upstream edge of the roof tile. These holes are meant to be ‘blocked up’ partially to make it more waterproof. On the tiles that need nailing to the batten, the roofer will put a nail through the hole and hammer it in (and in the process – clear the ‘blockage’).
You have nothing to do .
Jack
Hi,
Very interesting.
I have a leak that I think is due to chipped pointing and a blocked weep hole. I have found water pooling at the top of the tile when checking inside the roof cavity under the ridge cap.
Is there a way to clear a blocked weep hole? I’m thinking about pushing a wire through, would that work?
Thanks!
Hi Steve,
We have found that this neat little trick often works:
Buy a 6.5mm diameter (or similar close sized) masonry drill bit about 300mm long.
Put it on the end of a drill and use the rotary mode to clear out the weep hole. You do not need percussion (hammer) mode.
Hope this helps.
Jack
Hi
I have installed new colurbourbond flashings below a ridge cap line. And sikaflexed where flashing meets the ridge. This has covered weep holes I believe therefore creating a leak. These are flat concrete roof tiles with no real scallop to carry water. I assume either weep holes covered the issue or damaged/ blocked drainage channel lip?
Hi Michael,
You should not need to seal the colorbond flashing to the ridge capping – If you think that you need to do this, then there is a fundamental flaw in the design of the flashing.
Did it leak before you installed the flashing?
If it did not – then it is the colorbond flashing that causes the new leak… Not the weepholes (or lack of).
Hope this helps,
Jack
Hi Jack
I have a 24 year old Masterton home with Modern French Terracotta tiles. One of the roof tilers I have received a quote from to do repointing has recommended the drilling of weep holes in the bedding before repointing. There are currently no weep holes. As I am not able to go on the roof myself I cannot tell if the tiles under the ridge caps are full or cut. I think he is only proposing to do this on the top horizontal ridges. I am concerned that this could further damage bedding or tiles. What are your thoughts?
Value your advice.
Thanks
Hi Steve,
Only the top horizontal ridges need weep holes – if the top row of tiles has been cut.
Depending on the condition of the bedding on the top ridges (and how the ridges has been previously bedded), it is possible to establish weep holes by drilling with a bit of care.
Hope this helps.
Jack
Thanks Jack
So drilling weep holes in old bedding is not advised if the top row of tiles has not been cut? This is because? If the top tiles have not been cut then and the bedding is OK then a repoint is all that is needed?
Thanks
Hi Steve,
Terracotta roof tiles have a band of ridging on the upstream end for waterproofing and bonding purposes. These ridges prevent water seepage over the upstream end. When the tile is cut, the ridges disappear and the upstream has no resistance to overflow.That is why weep holes are needed.
As an aside, concrete roof tiles mostly have no ridging on the upstream end – so, it does not matter if the top tiles are cut or not – weep holes are always needed.
Hope this makes things clearer.
Jack