Rainwater Systems & Internal Gutters

It depends on the property. The main things that move the price are access — whether the work can be done off ladders or needs scaffolding — the material you choose, the size of the profile, and how difficult the spouting is to get to. As a guide on a linear metre rate, replacement spouting supplied and installed starts from around $50 per linear metre + GST for a standard-size COLORSTEEL profile, and runs up to around $150 per linear metre + GST for the larger commercial COLORSTEEL profiles. Marley uPVC sits between the two. There are also costs that only show up once we have looked at the building: scaffolding if the height or the site calls for it, any repair to the fascia, and whether the fascia needs repainting once the old spouting comes off. Those are specific to your property, so they are worth talking through with us before you commit to a replacement, and we set them out clearly in the quote.

Both are good products and we install both. Marley uPVC is the classic New Zealand spouting and suits a traditional Kiwi home, and it comes in a range of profiles including Typhoon. COLORSTEEL metal spouting is the more modern finish. It can be colour matched to a new long run roof and coordinated with the fascia and cladding, and on the right house it looks very sharp. It is most often installed as part of a roof replacement, while the access is already there. Which one suits comes down to the house, the existing system, how exposed the site is and the look you are after, and we will give you our recommendation when we look at the roof.

The short answer is replace it if it needs replacing. If it is old, cracked, sagging or the joins are failing, it has had its life. The less obvious case is spouting that is not quite there yet. On a two-storey house where the roof is coming off anyway, the scaffolding is already up and already paid for, so if the spouting is two thirds of the way through its life it is often worth doing at the same time rather than paying for access all over again in a few years. The same goes if the existing spouting is giving you grief, and there is nothing worse than listening to a drip late at night. Some spouting is still perfectly serviceable and worth keeping, and we will tell you plainly if that is the case when we quote the roof.

Most often it is simply blocked outlets, or gutters full of debris such as sticks and leaves. That is the first thing to check. But it is not always the cause. Older spouting can sag, brackets can pull away from the fascia, joins can fail, and low points develop where the water spills over the front edge before it ever reaches an outlet. On newer spouting the cause is usually different again. If there are very few outlets, the water has a long way to travel and not much fall to get there, so the gutter overflows before it has a chance to drain. That is not necessarily poor workmanship. It is often a limit of the stormwater drainage around the property rather than the gutter itself, and where new spouting has been installed to the existing layout the real fix can be additional stormwater connections so that more downpipes can be added. Working out which of these it is matters, because replacing old spouting with new spouting in the same layout will not fix a fall or capacity problem on its own.

It depends on the roof. How many outlets and downpipes a building needs comes down to the catchment area draining into each gutter, the size of the building, the gutter profile and the rainfall the system has to move. As a rule of thumb we would not want much more than about 12 metres of gutter draining to a single outlet, but that is a starting point rather than a rule, and every job is different. The practical indicator is how the system behaves. If the gutters are clean and well maintained and they still overflow in heavy rain, there is a good chance you do not have enough outlet or downpipe capacity for the roof above them. Internal gutters on commercial buildings are a different exercise again, and are usually specified by the architect or designer. On an older building the standard solution is not always practical, so the answer has to be worked out for that particular building. For the specifics, MBIE's Building Performance site and the NZ Metal Roof and Wall Cladding Code of Practice both cover roof drainage in detail. If you are not sure, get in touch and we will take a look.

Often you can, but it is not always the right answer. Say you are in a middle unit in a block of ten. Your section is rusting or sagging, so the spouting can be cut at the boundary with your neighbour, a join put in, and your length replaced. You will have new spouting, but you may not have fixed the problem. The spouting runs the length of the building as one system and it does not know where one property stops and the next begins. The fall, the outlet positions and the downpipe capacity are shared, so a new section in the middle of an old run is still working within the old layout. Where we can, we would rather get everyone on board and do the whole run at once, because that is the point at which the underlying issues can actually be sorted. That is easier said than done on a multi-unit property, but it is the better outcome, and we will tell you plainly which of the two you are looking at.

External spouting is fixed around the outside edge of the roof, so if it overflows the water generally spills outside the building. An internal gutter sits within the roof or the building envelope, which means an overflow or a failure can let water directly into the building below. That difference is why internal gutters need more careful consideration of capacity, outlet sizing, overflow provision, material choice and how the gutter will be inspected and maintained over the life of the building.

Common causes include corrosion, failed joints or detailing, blocked outlets, not enough fall, inadequate capacity for the roof area, and deterioration around sumps and penetrations. Because water entering from an internal gutter can travel some distance through the building before it becomes visible, the source needs to be properly investigated rather than assuming the first wet patch is where the failure happened.

Yes, and where the gutter is in poor condition it is strongly recommended. When the roof is off is often the only time anyone gets proper access to an internal gutter, so it is the practical moment to deal with it. Replacing the roof and leaving the gutter can turn out expensive. Either the roof has to come back up in a few years, or the gutter gets a remedial fix such as a smaller liner slipped inside the existing one, which can buy time but does not always pay off. Doing both at once avoids that. It does affect the programme though. Where the gutter is to be lined with a membrane such as TPO, the area may need temporary weather protection such as shrink wrap so the gutter can be rebuilt and the lining installed properly, which means the roof stays open for longer. That is worth knowing at the planning stage rather than halfway through, and we set it out in the programme before the work starts.

Yes. We work with architects, builders and developers on commercial and architectural projects. We can review the roofing and internal gutter details from an installation and buildability point of view, coordinate with the wider project team, and raise practical roofing issues before or during construction rather than once the work is underway. Where specialist structural or membrane design is required, that remains with the appropriate designer or specialist contractor.