In this article we will be looking at some of the guttering repairs that professionals like myself use on a day to day basis to repair damaged or leaking guttering. Some of these will be straightforward and easy to use, some will require a little skill. At all times extreme care should be taken when working on ladders or step ladders.
A lot the gutter repairs talked about here will involve Roofers mate which is an excellent long lasting product, can be applied in wet conditions, and is overpaintable too.
To speed up your navigation on this page I have included these on-page links. Clicking on these will shoot you down to the appropriate gutter repair, or you can just browse your way to the bottom if you are unsure. The average cost of having these jobs done by a professional is also listed at the bottom of the page, and in the quick links.
- What is the average cost of a gutter repair
- Things to check before taking your gutter apart – Why is my guttering overflowing – Is my guttering level – What to check before replacing my joints – I have gaps in my gutter, has it moved
- How to replace a gutter joint
- How to repair a plastic gutter
- How to repair cast iron gutters
- How to repair seamless aluminium gutters
- How to repair Concrete guttering
Often the first thing a homeowner notices about a gutter problem is water pouring over. Most often creating a noise while they’re trying to sleep, or bestowing unto them a wet head as they leave their house. The very first thing to check at this stage is that the gutter outlets aren’t blocked. This can be done by inspecting the junctions where the downpipes meet the gutter and checking for plants, balls, mud and other such things stopping the water from draining away. Next check for dirt in the guttering. If you have a lot of moss or dirt, or some roof mortar blocking the water flow, clean it out and test the gutter with water. If that’s all fine but the water still refuses to go away check the pipes aren’t blocked.
Blocked guttering – This is a standard build up of debris in the gutters and can be a common cause of water pouring over. Sometimes the gutter may appear clear, but as with the picture in picture, the outlet or ‘swan neck’ may be blocked.
Guttering not level
If after you have checked for blocked outlets and dirt, the guttering is still holding visible water, over 25mm (an inch), then you have poor gutter alignment. Each bracket should have a very slight fall, or at worse be level until it reaches the lowest part of a gutter run, the outlet. The installer should have ensured a constant ‘fall’ so that the water not only runs away, but cleans itself at the same time. If this isn’t the case water can quickly build up, overflowing in one, or multiple locations. This also puts an unreasonable burden on any gutter joins and shortens their lifespan as the water freezes in winter, expanding under the gaskets and adding lots of unnecessary weight. Often the only cure is to unclip the guttering where affected, and refit the gutter brackets with a spirit level. This often means lowering the outlet too.
Gutter alignment – By looking across the line of length of gutter you can assess the ‘fall’. Here is a particularly poor example where the outlet sits at the highest part. If there’s water in the gutter it will tell you the truth, if it’s not there, add some. If a water level was good enough for the Chinese, it’s good enough for me.
What to check before replacing a gutter union
Probably the most common guttering repair is to replace a plastic leaking gutter joint, often called a gutter union in the trade. The joints on a good quality guttering, depending on shape, should last anywhere from 5 to 20 years+ without dripping, but when they do, it is better to replace them with a matching joint rather than mess about with repairs if possible. But just before you do, check for the following…
- First check the union is clipped into the guttering correctly, sometimes they are unclipped at the back due to installer error, or the gutter has moved so that it no longer seats on the rubber gaskets fully – See gutter walking below. Correct either of these problems by reseating the joint and clipping it in before testing with water.
- The second thing to do is to inspect the joint and check it hasn’t sagged through a lack of support, this creates a dip which not only holds water but spraggs the rubber gaskets. If it has sagged, place a mug of water in the joint and lift it until it’s level. If the joint now stops leaking screw it to the fascia, there’s always a fixing point in unions, and they should always be used.
Plastic guttering is designed by the manufacturer to expand and contract with hot or cold weather. That’s why nearly all plastic guttering comes in a maximum length of 4 metres before it requires a union, angle, stop end, or outlet. All joints and angles have an internal marking showing a fitting point for the end of the gutter to sit on, and a physical stop, like a small upstand of plastic, to stop the guttering expanding past a certain point. During hot and cold weather the gutter slides over the rubber gaskets never going further than any of the physical stops. Simple.
Gutter walk – Problems can occur when the installer cuts a length too short, doesn’t screw a union to the fascia, or has fitted cheap guttering with poor design, overly tight gutter brackets, or poor joint clip pressure. As long as the gutter has not been cut short the guttering can normally be removed and re-clipped into position.
How to replace a gutter joint
The gutter repair below is the professional’s choice and also works on gutter bends like 90 degree bends and 45 degree bends (technically called a 135º offset bend)
I have read on the internet people talking about replacing gaskets inside gutter joints rather than the whole joint. Honestly, don’t waste your time, the only time I would do this is with gutter profiles you can no longer buy. It’s much better to replace the union as a whole. Time taken going to buy the gasket alone just to find that part of the union breaks when you go to clip it back together isn’t worth the effort.
Look for a makers mark under the part, often it’s printed on the part itself. Failing that, move over to a gutter bracket and look there. The only common manufacturer I know of that can make it cryptic sometimes is PolyPipe who may just have a ‘P’ symbol in a circle. Now just go and get the part from a building plastics company or via the internet if there are none near you.
If the guttering is standard 112mm half round profile you can usually make any manufacturer’s part fit as they are interchangeable, which is great becuase your local DIY chain or Screwfix will probably have some in stock. As a Pro tip I would strongly favour a gutter brand such as FlowPlast or Polypipe, as some of the other brands can leak prematurely through poor design.
How to repair a plastic gutter joint
There may be times when the guttering is old and you simply cannot get the correct part. This can happen with some old gutter profiles like early half round Marley guttering, or some more complicated designs. Often I see tradesmen and homeowners use a silicone sealant applied directly onto a rubber gasket and then they clip the union back together so the silicone sticks to the underside of the guttering.
While on the face of it this seems logical, it’s often a very poor idea. Gutter joins are designed to allow expansion and contraction, which is a force of nature that silicone, or any glue cannot stop. As the gutter expands and contracts with temperature the gutter rolls back and forth over the silicone bunching it up, splitting it, or popping it loose over time. This obviously works against you.
A much better and longer lasting technique, is to lift the rubber gaskets from the gutter joint and seal them back into their seats, with the silicone beneath them. This sits the rubber gasket slightly higher and increases the clip strength, solving the leak. It goes without saying that all components should be dry and dirt free to work effectively. If you are trade and need to effect a repair in the wet, as happens sometimes, carry a tube of Roofers mate. As long as you remove all traces of dirt and algae it even works in the wet.
How to repair cast iron guttering
Cast iron, as long as it is not full of rusty holes, does open up a couple of viable options depending on skill level, patience, and gutter condition. Let’s go with the best, but more tricky solution first…
- Remove the bolt clamping the sections of cast iron together at the leaking union. Getting the bolt out either entails unscrewing the nut on the underside of the union with some Vice grips, or cutting the nut off between the cast iron gutter and the top of the nut, then punching the remains of the bolt out from underneath. Or both of these. It can be easy, or it can be tiresome. A multi cutter works wonders instead of a hack saw but avoid any sort of angle grinder because of the sparks generated near the roofline.
- Now carefully split the joint by hammering in a slot head screwdriver in the open side of the joint. You should now be able to clean out the old dry putty, which again will be easy, or tooth gnashingly tedious. Do not excessively lever the gutter up at this stage or you will break any other non leaking unions. Try to work with no more than a 15mm gap maximum.
- When the joints are clean and dry squeeze in some paintable sealant like Roofers mate and remove the screwdriver holding the male and female joint apart. Traditionally putty can be used, but, it’s an even bigger faff to work with.
- Don’t forget to place some sealant or putty under the head of a new roofing bolt before you place it through the hole in the joint. This stops possible drips from the bolt later. Lastly gently tighten up the nut underneath to a generous pinch, too much pressure risks cracking the cast.
Cast iron gutter joint repair – This may seem long winded, because it is, but a surprising amount of joints can be done in a day with very good long term results. Ive seen this last over 30 years, as long as the general condition of the cast is good.
Repairing cast iron gutter part 2
This is a much faster repair and works on cast iron gutter that is in quite poor condition, aka its last legs.
- Make sure the affected leaking joint is clean and dry, and that the bolt is not loose or missing.
- Wire brush and then soft brush 75mm (3″) either side of the joint.
- An optional flashband tape can then be applied, but it may need to be adhered with heat for best results. Cut some flashing tape that covers a minimum of 50mm each side of the joint and stick it in place. On a very hot summers day it will stick of its own accord very well, but any other time it will not and you may need to stick it down with a heat gun. If you are not insured to work with heat, skip this step. Burning your house down is embarrassing.
- Paint on some Acrylic fibreglass reinforced paint like Acrypol or Evercryl. After working the sealant into the cast iron to ‘prime’ it and bind any dust, try to maintain an application depth of 2-3mm for the entire 75mm of the repair either side of the joint.
This is obviously much faster than the repair above, but not as long lasting. I would expect to get anywhere from 2 to 5 years, maybe more. While a repair like this will not have a predictable life span, it does have some merit.
Continuous aluminium guttering repair
Unfortunately as you have probably come to realise if you’re reading this, continuous guttering isn’t actually continuous. All the corners and drain pipe outlets will be joined with a sealant and rivet system, which from time to time leak. These are what’s known in the trade as a ‘Git’ to repair. There are two sensible methods of repair, with the easiest, being similar to the second cast iron repair listed above. So where to start? Well the difficult way as always…
- Drill out all the rivets securing the corner or outlet. A long drill bit the exact same size as the rivet body is often required to reach any awkward rear rivets (approx 3mm).
- It’s now a matter of squeezing a thin strong blade between the mating surfaces and breaking the affected part loose. This can take 5 minutes or 30 minutes. Patience and thought is required, along with some gentle levering with a thin flat bladed screwdriver now and again, all without damaging or bending the thin aluminium.
- Some fixings to the internal brackets close to where you are working may need to be removed from the length you are working on, this allows you to twist it out of position to work, sometimes it’s easier to remove the whole length.
- When free, clean up all mating surfaces and apply multiple thin beads of a gutter sealant like Roofers mate and squish all mating surfaces back how you found them.
- Rear fixings can sometimes be screwed rather than riveted into the fascia for ease, then rivet all outer fixings with a pop rivet gun of the same size.
- If there are any small lifts or niggles with the aluminium that look odd, beat them with a small plastic mallet with a cloth over the end, and a block on the inside of the gutter to hammer against.
- Any silver rivets or scratches can be touched up with a satin car paint. If you use a spray like me, spray it into the cap, allow it to evaporate off slightly, and use a small brush to make good any bits and bobs.
Split and seal – This method isn’t quick or easy, especially on this style of continuous guttering with large overlapping joints. But it should last another 20 years if done correctly because the sealant packs out all mating surfaces of the joints.
In this video of an aluminium gutter repair, I have scraped off all existing sealant and re-sealed with a good quality sealant. A simple self adhesive plasterers scrim was also used to ensure an even application depth.
How to repair concrete Finlock guttering
Finlock guttering, otherwise known as Concrete gutters, can be a royal pain to repair. On the face of it concrete must have seemed a great idea initially, the reality though is a lot different. To avoid the concrete guttering splitting or cracking with expansion and contraction they had to be made in sections, and each section provides, well guarantees, a potential leak in old age.
Hand on heart it is very difficult to think of a practical simple repair to a concrete gutter joint that has a guaranteed lifespan of over 12 months. Temporary, ‘I’m selling the house’ solutions often involve painting the inside of the gutter or joints with bitumen primer, then bitumen paint. Or an acrylic paint as talked about in the cast iron gutter repair above.
More permanent solutions really come down to either a costly removal and fitting a traditional fascia and guttering, or simply lining the Finlock gutter with another material. These include…
- Torch on bitumen felt – This can work very well, but personally I don’t like hot flame near exposed roof rafters and felt.
- Fibreglass – Will work as long as the concrete has not been contaminated by previous repair substances like masses of bitumen, flashband and Torch-on felt.
- EPDM rubber – Works very well as long as the joins on the rubber are made well and the install is of a good quality.
- Polymer – A good quality polymer system should also work well depending on the system used. There are just so many versions of this now it’s hard to keep track, or score whose is best. Often the same product is rebranded and marketed under a different label as well.
Average cost of a gutter repair
These costs below are based on a large city in the Midlands, which has always proved to be a good national average. The average price of repairing a gutter may go up if the work is hindered by conservatories, extreme height or other obstacles that could mean the use of scaffolding. Large cities like London can also increase the cost of small repairs by up to double.
- Cost of replacing a gutter joint – Standard plastic gutter designs in ‘off the shelf’ colours are easy to get, so expect to pay around £50 for fitting one or two unions, and around £50 per hour labour after that. Specialist colours or styles may be special order and will increase the cost.
- Price of unblocking a guttering downpipe – This can range from plucking a tennis ball out of a downpipe for £40, dismantling a plastic pipe £50 to £100, to full scale pipe removal and refitting for extreme blockages. That can be £50 per hour, and the cost of a drain cleaning company if it’s blocked below ground.
- Cost of repairing cast iron joints – Usually about £40 to £90 per joint depending on how difficult they are going to be, and if you are splitting and re-sealing them with new bolts. Simple paint on solutions will be at the lower end of the scale.
- Price of seamless gutter repairs – These are tricky. I would charge around £100 per joint or angle to split and re-seal, £70 for a better repair with gutter sealant and scrim, whilst simple paint on repairs usually come in at about £40 per joint.
- Cost of concrete gutter repair – For a simple paint on fix, prices tend to be around £40 to £50 per joint. For cleaning and sealing a whole gutter with bitumen or a sealant, expect £30 to £50 per square metre on average. Lining the gutter with Torchon or another system will cost approximately the same cost per metre as above but with the addition of the material cost of your chosen lining system on top, plus any scaffolding required.
- Price of Finlock gutter removal – Replacing Finlock gutters with a traditional fascia and guttering is time consuming and dirty work that requires full professional scaffolding. The cost of removing finlock gutters and installing fascias, and new guttering is approximately £300 per metre, depending on the design of the old concrete guttering.