what is a box gutter

What is a box gutter?

If you can’t see your roof gutter from ground level, then you probably have a box gutter that is ‘boxed’ into your roof.

Most houses don’t have box gutters. They have gutters running around the external perimeter of the roofs and these are called ‘eaves gutters’ (even though some houses now do not have eaves).

A box gutter may look like a box because of its ‘boxy’ shape. But the main reason  for its name is because it is ‘boxed in’ on all sides. The picture above shows the layout of a typical box gutter on a metal roof.

Typically, a box gutter is ‘trapped’ between two roofs that feed rainwater into it. The water is drained via downpipe nozzles, or via a sumps & downpipes built into it.

A good box gutter design will have falls along its length, together with sumps to collect water before it is fed into large downpipes. There will also be an overflow facility on the side or the end. This is very important – so that water will overflow externally to the building, rather than flood into the roof cavity.

The best box gutter design has full width discharge ends. These pour water into rainwater heads on a wall outside the building. There are no internal downpipes and sumps to block up and cause overflows.

What is the best material for a box gutter?

I recommend that (as a minimum) colorbond should always be used. Some severe situations may call for colorbond “ULTRA” or even colorbond stainless…. although care against cathodic corrosion is needed with stainless.

Box gutters get a lot of moist leaves and debris and these can shorten its life – so the rule of thumb is to have the box gutter material as good or better (in the corrosion department) than the roofing material.

Sometimes I see architectural specifications nominating a colorbond roof with a zincalume box gutter. This combination can result in much higher maintenance costs for the roof.

Why?

…Because, the box gutter will need replacement a lot sooner than the roof. And a box gutter replacement is quite expensive and time consuming – because it usually involves removal of the roof sheeting.

It is easier to replace a box gutter together with the roof . Doing it with the roof in place is much more time consuming and costly.

Can box gutters be eliminated?

Unfortunately, with flat roofs, larger complex roofs, parapet walls and other architectural building features, rainwater does not always drain out directly to the external perimeter of the roof.

In these instances, box gutters are the only viable option. So, if your roof is not ‘straight forward’ – then you probably have a one of these somewhere on it.

There is no need to stress out about box gutters…if they are designed correctly with overflows and you carry out regular maintenance.

It pays to have these gutters maintained and regularly cleaned out – simply because a box gutter leak has much higher consequences. Water will go into the house!

Whilst with eaves gutters along the edge of your roof, the water just pours outside when it overflows or leaks.

Are box gutters expensive?

There is a lot more work involved.

There is more thought needed to get a design right and the roof framing tends to be more complex.

Because they are much bigger than eaves gutters, the material cost is greater. 

It will certainly cost you more (for the ceiling and internal repair works) if it leaks.

And it takes longer to replace one….

So, the answer is YES. 

…. But you may have no option. And if this is the case, then make sure that it is designed and installed correctly in the first instance. Then be fanatical about keeping them clean!

Do you have a leaking box gutter that needs repairing?

Box gutter repairs are often the first option available for you. There are things to keep in mind if you are looking at box gutter repairs. 

Most factories have box gutters and many houses with edge parapet walls have some type of box gutter that either needs repair of replacement.

When box gutters leak, there are two ways that you will experience the result:

  • A deluge of water inside the property during a heavy rain or…
  • Slight dampness progressing to constant drips over a length of time.

Box gutter repairs for that deluge leak.

If you get flooded inside the property during a heavy downpour – then you have a blockage somewhere along your box gutter.

Box gutters in factories usually have sumps to collect the water and force it down the downpipe.

If the box gutter and sumps are not maintained regularly, you will get this….

Leaves will choke the drainage from box gutters and cause leaks

There are design standards for sizing of box gutters and downpipes. But these designs assume no blockage. It does not matter how large the box gutter is – it will overflow if the downpipe outlet is blocked.

You don’t have trees?

Well, we once found a box gutter sump blocked by the combination of a sweets wrapper and a old coke can. It does not take much to cause a blockage…

There is a leaking hole at the edge of the sump. The Coke can made things worse,,,

At least these box gutter repair situations above can easily be fixed by a bit of clean up work.

What about overflow insurance?

You may want to sleep better during those stormy nights (after feeling a bit guilty about forgetting to clean your box gutter). If you have overflows in your box gutter, you can go back to sleep.

If you don’t – then you will need to seriously consider this option. An overflow is the most effective box gutter repair method to counter the sudden deluge leak.

A new overflow is the best box gutter repair option
  • Leaking joint
  • Rusty box gutter

Very often, sealants break at the joints or pop rivets break off. Water will weep constantly during any intensity rain.

The repair is quite simple.  Clean the box gutter joint and re-seal.

The rusty box gutter has a temporary solution. A quick patch of the rusted areas will keep water out for a short while  – and allow for preparations for a proper job. Which is…a full box gutter replacement with a colorbond box gutter.

Keeping the water out by a temporary patch over the rust holes

The main thing with box gutters that show premature rust is to find out why.

If there is ponding water – then the new replacement box gutter should not copy this error.

Proper falls to the outlets will increase the life of the replacement box gutter.

Box gutter sloping the wrong way

Box gutter repairs – the way forward

Putting overflows into box gutters or designing box gutters with a full with discharge through the parapet wall into  rainwater head is the best ‘bank for bucks’ – if you have a overflow problem.

If the box gutter is locally rusty and need replacement, then it pays to find out why it has rusted prematurely and have these factors eliminated with the new box gutter.

Talk to a professional

 
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James Finn
James Finn
8 years ago

Hi
Looking at the “typical shape” of a box gutter in your iliistration, I note that there is no flashing shown, its simply a “u” shape…is this a normal design ? and if so what stops the water from a down pour overflowing back under the roof ?

jackyuen
jackyuen
8 years ago
Reply to  James Finn

James,

It is quite normal for a box gutter to be a simple U shape. There is nothing stopping overflowing back under the roof.
That is why it is important to have box gutter overflows and sufficient downpipe outlets to stop the water line approaching the top edge of the box gutter.
Box gutters are not as good as eaves gutters because the overflows go back into the property rather than external.
That is why particular care with design and maintenance (to prevent blockage of the drainage outlets) is critical when you have a box gutter on your roof.

Jack

jane sabine
jane sabine
7 years ago

WE have had a box gutter for new extension roof where it joins gable end of our existing building. However, the new extension bedroom corner wall has become very damp and new paint is now peeling off. There is no leak on roof tiling. I can only think the box gutter is tipping rainwater towards inside block wall although the external wall on both existing and new extn wall are also very wet. Any help would be appreciated to find out the cause, do I need the chippies back to sort it, or is it the roof tilers?

Stuart
Stuart
7 years ago

Greetings Jack. Planning to construct a roof between twi existing buildings approximately 1.8 metres across from shed to shed. Intend to slope roff from left to right. Will be attaching the roof support frame to the walls of each shed, approximately two thirds up the side of each shed. Intending to install a box gutter. Despite a very significant eave on the existing shed, on the box gutter side. Will need to flash both shed walls to prevent leaking. Both shed walls are external walls, clad with colorbond sheeting. Would screws and silicone be sufficient? Any advice would be appreciated. thanks in advance.

tommy
tommy
7 years ago

can i replace box gutters with stander gutters i dont care about how the house will look.

brendan
brendan
7 years ago

Hi,

Looking at purchasing a property with box gutters and wood fascia. The wood fascia has some rot and some of the downpipes may be blocked with leaf litter. Would you know if the fascia replacement is expensive to fix. The roof itself is in good condition

milan
milan
6 years ago

i need a detail drawing of a box gutter to a brick partition wall (car port wall on the boundary) thanks

petrina
6 years ago

recently we had a roofer come out and install a box gutter in between two buildings however it still leaks we have put two downpipes from each end of gutter but still no luck . can u help please?

Arthur Murphy
Arthur Murphy
6 years ago

Can you or is it legal to put a side outlet out of a roof sump and not use pops as outlets

Chris
Chris
6 years ago

Hi There ,

I am just having a box gutter installed on our house that is being renovated at the moment .

The roofer says that by Australian Standards the colourbond box gutter insert must sit on either a plywood or AC sheet base to be compliant .

Is this correct ?

Thanks

Alka N
Alka N
6 years ago

Our townhouse is 5 years old with a box gutter. After the recent heavy rains,the water came from the roof into the bedroom like a curtain waterfall down two walls, and also leaking down into the ground floor. After cutting open the ceiling, the water was found to be coming down between the wall and the brick outer wall. The plumber has put bitumen on the gutter joint, which has not helped, as the water leak has not stopped completely. Could you advise what needs to be done. Thanks..

Leo
Leo
6 years ago

Hello.
I have a 79 year house with galvanized box gutters, I noticed water is pounding in the middle. Is this normal for box gutters or should they be adjusted to run off better.

Chris
Chris
6 years ago

My sons home is only 4 years old and has a flat roof with box gutters when we had a bad storm mid April 2015 we had lots of hail very small built up and block the drains causing water to pour into house bedrooms plus. How can we correct this happening once again.

Ethan
Ethan
5 years ago

Hi Jake,
Hope you are well.
I recently replaced my old box gutter. However, the new one doesn’t have enough fall to let water flow to downpipe. The tradesman said that they cannot make enough fall as box gutter need to align with eave. My eave doesn’t have enough fall. Is this true?
The new box gutter blocks old overflow point. The tradesman said that it is a more advanced system ( the front of new box gutter is lower than the back). No overflow point will be required as the water can over flow from the front of box gutter. Is this true?
Thanks for your time.

Maz
Maz
5 years ago

Hi,
We have a box gutter on our new renovation. It is 9 metres long. The pitch is sloped slightly the wrong way at the beginning causing a few mm of water to stand there for many days after a rain. Is this bad for the gutter? Is this compliant?

paul walton
paul walton
5 years ago

I have installed box gutter in a church .it was originally installed the same as previous box gutters .They were not happy that it held water so they wanted a fall on it .So I had to take out again and cut one side down and indoing so cut the turn down of to get a fall .My question is ,because I had to cut it down to fit it so it has fall it dosent have the turndown ontop edge , does it void there warranty?

Hilton
Hilton
3 years ago

Hi Jack
My son is building a house which has a surrounding parapet on the front and sides. They are using standard 1/2 round gutters of 150mm. Iits a flat colourbond roof and i am concerned these will not cope in a big downpour. Any ideas on this. The buikder says if it overflows it wont come in the house. What questions and warranties should we try and get from him. Many thank

Hilton
Hilton
3 years ago

Hi Jack
Thanks for the advice. All the best
Hilton

R. Bassett
R. Bassett
3 years ago

Thanks for the advice here, it is very useful. We are going to have an unavoidable box gutter about 8m long, with one down pipe of 100mm, draining a pop up roof that is about 8 x 5m. There are a lot of gum trees above and maintenance will be high. I’ve had conflicting advice about gutter guards. Do you recommend some sort of gutter guard or will this make cleaning more difficult?

Jeremy Horrocks
Jeremy Horrocks
3 years ago

Hi Jack,
My roof is a flat roof with box gutters and very little fall, definitely less than 5 degrees. In heavy rain there is no problem but in light rain the water seems to go back up under the sheeting and drips into the eaves. My question is: is there a product that I can slide up under the sheeting to stop this back-flow problem?
Thanks,
Jeremy

Jeremy
Jeremy
3 years ago

Thanks Jack,
One local roofer just quoted $800 to fix the problem!
I will try to locate the turn down tool and do it myself. Worth a try!!

Lovely s
Lovely s
3 years ago

Hello, I have a older home 1910 in Pittsburgh,pa! I notice several leaking areas in my house and was told it’s my box gutters. I have build in box gutters. Some say repair while other roofers say replace them because repairs are short term. I was told my box gutters in the back is bad. Money is tight and I want to stop water from leaking into my house or side of building! My house is about 2300 sq. I was also told I can get rid of the box glutter system all together and than do the regular hang glutter. What do you think? I do not care about the look of the house!

deborah Joanne
deborah Joanne
2 years ago

Hi there,

we are really at the end of our tether. We had a conservatory installed 2 years ago and usually in the winter months it leaks a great deal more in one place. This is in a corner which takes a lot of rainfall from the main roof and it fills up very quickly. Also I don’t feel as though the drainage to the down pipe is quick enough. However, when we have spoken to the company who erected it, they say a box gutter should not have a fall on it. On dry days significant water pools in this area without draining away. I am wondering whether the gutter needs more fall on it and whether a wider box gutter is needed to take away the volume of water we get from the main roof. How would you recommend we try to get to the bottom of the issue. Also we have the issue of condensation as no trickle vents were ever fitted and a build up of moisture is occurring under the aluminium gutter causing the insulation underneath the box gutter(inside) to become damp.
Any suggestions would be most welcome

Rubyet Rahman
Rubyet Rahman
1 year ago

Hi jack
We are currently building with a project builder. we loved the look of parapet. and apparently builder using box gutters. And reading all the reviews I am worried if it was good idea ot problems to come . please I would like to provide with some details of the design and get your advise on if they are doing the right thing.
warm regards
Ruby

Nicola Worthington
Nicola Worthington
1 year ago

Hi Jack
Thanks for your help. I have just had my whole flat roof and gutters replaced. I have box gutters and noticed that the overflow spouts in the old system were not in the new system. I’m worried that there are no overflow provisions at all and when I asked the contractor he said he didn’t keep overflow spouts as he didn’t think I would like the look of them. This did not give me a great sense of confidence. What I should be asking for or expecting in relation to overflow provisions for a large flat roof with 5 x 90mm downpipes? Cheers Nikki

Erik Sanders Wayne
Erik Sanders Wayne
1 year ago

Hi Jack!
My house has a metal roof with pretty old box gutters.
Is it possible to have the box gutters removed and replaced with seamless modern gutters that are a lot cheaper?

I saw online its not expensive to install seamless gutters but not sure if a lot of labor hours could be involved in the removal of the old box gutters and if the removal can be pricey?

Greg
Greg
1 year ago

Hi jack

We have a box gutter above our bedroom. Every night it drips. I assume it’s from condensation. The sound echos and keeps us up. Are there any methods of stopping the dripping. Or the sound? Thanks. Greg

Anthony
Anthony
11 months ago

Hi Jack,
We’re under construction now, lock up. When we’re in the house, we notice how loud the box gutters are with the wind. The colorbond roof sheets banging the top of one side of the u shaped box gutter. Maybe when we’re insulated and plastered it won’t be as obvious, but is that normal?

Pene
Pene
8 months ago

Hi jack
I have been quoted $6500 to replace a box cutter – I think about an 8m section – They said it would be a days work for one guy
Does this seem reasonable to you. Thanks also for your message board – for someone who is clueless like me it really helps to get advice – not sure if I’m being fleeced
Thanks
Pene

Adele
Adele
6 months ago

High I have box guttering in my conservatory. The firewall side now had a drip running. Not always there, noticed it in cold days and not so much when raining. I have had a roofer up and put hose up for over an hour and no leaks evident. Wall had to be plastered due to being wet and now I have noticed another drip on the plaster. Is this due to condensation?
Thanks
Adele

Herb
Herb
5 months ago

Hi Jack,
I stumbled on your website through a google search trying to decide whether on box gutter design versus normal quad gutters. Currently in concept design with my architect who has designed with box gutters however i reading more and more into it they appear to have a bad wrap. Last thing i want is to invest in something new only to have problems (leaking walls etc.) later.

Based on your knowledge & experience, would you recommend against a box gutter versus normal quad gutters given the option?

Appreciate your reply.
H

Simon
Simon
3 months ago

Hi Herb,
I have a flat colour bond roof with a box gutter flowing into a rain head at one end. Above this roof and is a wooden deck. The box gutter is leaking into the ceiling of the room below. That said, as access from above is obstructed, is it possible to repair a box gutter from the underneath (I.e. through the ceiling of the room below)?
Thanks