How to adjust the slope of my roof guttering?

[kanga25]

Part of the roof guttering is not allowing water to flow towards the downpipe and is subsequentially pooling in the guttering. How do I adjust the guttering to give it the required pitch/slope towards the downpipe?

[MitchellMc]

Welcome to the Bunnings Workshop community @kanga25. It's wonderful to have you join us, and many thanks for your question about adjusting the slope of guttering.

Typically, you'd need to remove the guttering and move each bracket up incrementally, starting at the far end from the downpipe. Another reason for the water not flowing correctly is that there are not enough brackets along the length. So, if water is just pooling in a midsection, you might require another bracket to lift that specific section.

You can stick a garden hose in there to check that you have an adequate fall. You'll be looking for at least 1:500 for eave mounted and 1:100 for box gutters.

Please let me know if you have any questions.

Mitchell
 

[kanga25]

Just following up on this. I have been having issues getting a roofing/guttering tradie for this job. I may need to have a go myself. Just a couple of questions. When you say "move the clips up", what do you actually mean. The water does seem to be pooling between mid-point to to furthest point from the downpipe. If I add clip(s) in mid-point, won't that increase the slope between mid-point to high-point, and exaggerate the problem I am trying to resolve? Thanks for any advice.

[MitchellMc]

Hi @kanga25,

So, if the downpipe is on the left and the water pools in the middle, the middle might have sagged. Adding a clip in that section and raising the gutter would push the water to the left and downhill; the right should already be higher than the left. However, if the fall over the entire length is inadequate, you are correct that simply raising the mid-section might continue to hold the water there or push it to the right. The simplest explanation, provided the gutter was installed with the correct fall, is that the midpoint has sunken. You need to take some measurements over the whole length of the gutter to determine what is going wrong. There should be a consistent fall over the whole length.

If you raise the right-hand side only, you might still have a midsection that is too low, trapping the water. Perhaps take some measurements from the ground to each 1000mm point along the guttering. Write those down, and you should soon be able to see what the issue is. If the height does not consistently rise from the midpoint until the end on the right, one would think that everything past the midpoint needs to be raised slightly.

Mitchell

[kanga25]

Thanks Mitchell, I'll investigate further based on your advice, and hopefully I can resolve the issue. Regards Jim.

[kanga25]

 

Hi Mitchell, just a question about these gutter straps. Just to confirm these are the correct ones? Also, I assume the back wraps around the outside of the fascia/gutter and, if so, the pre-drilled holes are redundant because I cannot get to them. Am I on the right track or off the rails? Thanks.

[MitchellMc]

Hi @kanga25,

Those are internal gutter straps. Do they look the same as your current ones? The alternative is the older-styled external straps. Both of those styles are designed to be installed before the guttering is clipped into them. So, unfortunately, the fixing holes are not redundant, as you'll need to remove the guttering to install the straps. Bit of a pain, I know.

How'd you go with those measurements? Does anything seem off? 

Mitchell

[kanga25]

Hi Mitchell, the current ones appear to be old internal style and not the same as those shown in last post (house was built in 2010). Here are the measurements. I used the fascia as the reference, and even if allowing for a slight error with reference/user accuracy, there is a significant fallaway at a few points.

Distance                   Fall/Pitch

High Side

1m                                   +4mm

2m                                   +7mm

3m                                   +6mm

4m                                      0mm

5m                                   +2mm

6m                                   +1mm

Low Side

[MitchellMc]

Thanks @kanga25.

So, the high side is significantly higher than the low. It does look like a bracket at the 4m mark would correct the issue. Raising it to +4mm should do the job.

Mitchell