weep holes for tile roof

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 are:

  • 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 have a longer guarantee if new weep holes are installed and a shorter warranty with no weep holes.
If the hips on a tile roof are built correctly, no weep holes are required

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 MAYBE. I have experimented with the use of a long (300mm or longer) masonry drill bit (5mm diameter) and there is a reasonable success rate. In normal (low cement content) bedding, this will produce a weep hole along the top surface of the roof tile quite easily.

However, If high cement ratio bedding has been used, then there is going to be some destruction. Drilling will not work in this instance.

Weep holes re-instated 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…

Addendum December 2019

There has been a lot of interest on weep holes for roof tiles and I am adding this bit of information to make more sense of this topic.

How to make weep holes:

This is the proper weep holer with a larger prong to do the bedding hole and a smaller one to reinstate the weep hole after pointing

I have always manufactured my own weep holers using ‘butchers hooks’. But rather than showing this manufacturing process, it is far better to show you what an integrated weep holer looks like and where to get one.

Hytile in Victoria manufactures a weep holer that you can purchase online. One of the prongs (the larger one) is used to make the hole in the bedding and the other is used after the pointing is done. The theory is that it is easier for a smaller prong to re-establish the weep hole through the hardened bedding – and it will smear a little bit of pointing into the circumference of the weep hole to better stabilise it.

Why no weep holes along the hips?

why no weep holes on ridge capping at hips
Weep holes are not needed under the hips because trapped water flows across to the water course of the adjacent lower tile

Weep holes are not normally needed under the ridge capping at the hips of the roof. Water that seeps in under the ridge capping starts to pool at the troughs of the roof tiles – but before they can overflow the top of the triangular cut, the water trickles over the adjacent downstream hump.

…. one of the wonders of gravity.

This keeps happening until the water finds a side lap on the roof tile. The water then runs into the lap and down the water course, making its way outside the bedding.

But gravity can only do its trick under normal roof conditions. When the roof gets too flat, water can overflow the cut edge before it has a chance of running down the hip to the tile lap. This is why tile roofs are no good if laid too flat.

Another abnormal condition happens when the original roof tiler cuts one of the hip tiles too short. This reduces the capacity of the cut roof tile to store water before it can trickle downstream. The resultant leak over the cut edge then happens.

Yet another abnormal condition exists when excessive (width) bedding is used. The excessive bedding also ‘eats up’ the storage capacity of the cut roof tile and results in very little resistance to overflowing leaks.

… And we all thought ridge capping was a simple job!


There are times where weep holes are not the problem. We have found many other situations where roofs leak near ridge capping. To find out how we can help you find out what sort of roof repairs you need, start at our HOME page.

 
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dave
dave
7 years ago

video was great but the music is louder than the commentry

Tony
Tony
7 years ago

Thanks Jack very educational. I learned lots. cheers. Tony

john
john
6 years ago

Are weep holes a Australian standard or requirement??

Thanks

Sue english
Sue english
6 years ago

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

David
David
6 years ago

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

john
john
6 years ago

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.

Barbara
Barbara
6 years ago

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.

rohan
rohan
5 years ago

Can you please tell me how deep should I drill for concrete ridges and what diameter the bit should be. Thanks very much

john GU
john GU
4 years ago

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

john
john
4 years ago

Hi,Jack
Thank you !

john
john
4 years ago

Hi, Jack
Could you please explain how to drill weep holes in ridge capping around? If there were no weep holes
Thnks

Patrick
Patrick
4 years ago

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 ?

Steve
Steve
3 years ago

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!

Michael
Michael
3 years ago

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?

Steve
Steve
3 years ago

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

Steve
Steve
3 years ago

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

Jan
Jan
2 years ago

Hi Jack

Are you able to recommend a professional roofing in company in Auckland, New Zealand, that can put weep holes in a concrete tiles? My roof was repainted two and a half years ago – about 3 months ago damp spots appeared on my inside ceiling along the ridge line. My house is joined to my neighbours and I went a long with his choice of roof painter. The trusted firm that does my regular moss treatment isn’t prepared to even give me a quote for putting in weep holes. I’ve looked at your video and read all your comments but I’m a bit confused about terms like pointing.
Thanks, Jan

Jamie
Jamie
1 year ago

Hi Jack,

Great info!! I have a coupkle of questions though. How did you put the initial holes in the bedding? And also how come you dont need weep holes down the hips to the external corner of a roof, just the horizontal?

Kim
Kim
1 year ago

Hi Jack
I am seeking to find information about the Australia. Standards including when these came into the standards as well as where to get a copy of these standards. Any hello to dons this information would be greatly appreciated .
Kim

Stewart Melville Dowling
Stewart Melville Dowling
1 year ago

G’day Jack,
Can an insurance company insist you have weep holes inserted in the hip ?
Stew

Greg Keena
Greg Keena
1 year ago

I have a tile roof with bird blocking on the bottom side. The metal bird blocking has a weep hole every two feet. I just discovered that most of the weep holes are plugged with dirt. I’ve been cleaning them out the best I can. Any recommendations to get these clean?

Robert Stevens
Robert Stevens
1 month ago

Fretting of the underside of tetta cotta roof tiles in Adelaide is caused by salt obsorbing moisture from the air – its the same process we call salt damp in walls. The salt is in the clay tile to start with and our climate sets up the reaction.