Rainwater Gutter Installation Guide

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Rainwater Step by Step Installation Guide - GUTTERING

To position the running outlet accurately, hold a plumb line against the fascia directly over the drain. 
Mark the position on the fascia with a pencil.

Fit the outlet no more than 50mm below the level of the roof tiles.

Fit a fascia bracket just below the top of the fascia board at one end of the run of guttering (opposite end of the outlet) 
Tie a plumb line (string) around the base of the bracket.

Stretch the plumb Line from the bracket along the fascia board and tie it to the outlet. 
Using a spirit level, check that there is a fall towards the outlet (1.350 is recommended) to encourage water to drain efficiently.

Mark the position of the fascia brackets, spacing them no more than 800mm apart (600mm in areas of heavy snowfall) and no more than 150mm from any angle or stopend.

Fix the rest of the fascia brackets

Use two 25mm x 5mm  round head brass or zinc screws when fitting fascia brackets.

Starting at the outlet, fit the first length of gutter using the ‘back to front’ rule (see below).

Fit a union bracket at the other end of the first length and screw it into the fascia, then fit the next length of gutter into it.

Continue joining lengths. 

Make sure all joints line up with the insertion depth marked in the fittings.

‘Back to Front’ Rule:
Tilt the gutter to fit under the back clip and snap in at the front.

Cut the last section of gutter to fit using a hacksaw and fit a stopend


Rainwater Step by Step Installation Guide - DOWNPIPES

Using a plumb line, mark a vertical line on the wall from the outlet to the drain.

Hold a downpipe clip centrally over the line and mark the fixing holes on the wall with a pencil.
Repeat down the wall, spacing pipe clips no more than 1.8m apart.

Drill the fixing holes.

Use wall plugs when fitting pipe clip screws to ensure that the application is secure.

Working from the top downwards, install the downpipe. If additional lengths of downpipe are required, join using a socket and pipe clip

Leave a 10mm gap between the end of the pipe and the bottom of the pipe socket to allow for expansion.

Fix a pipe clip over the joint.

Fit the pipe clips to the downpipe and screw them into the wall.

Secure pipe/socket clips with two 32mm x 6.5mm screws.

Fit the shoe at the bottom of the downpipe so that it directs water into the drain, if required.

Secure the joint with a pipe clip.

Use lubricant on all gutter seals for ease of fitting and for improved performance.


1. Plan your installation using the component pages on this site to assist you in selecting the correct type and quantity of products required.   


Fascia brackets should be spaced at a maximum of 1000 mm  apart on straight 
Gutter runs on square and round guttering and 800mm apart on Ogee Niagara and Industrial Guttering.  

Angles and stop ends should have a fascia bracket within 150 mm of the fitting A supporting pipe clip should be used on shoes branches and offset bends to prevent the down pipe from slipping Down pipes are best fixed at 1 metre Centres.   

2. If you intend to cover your old timber with UPV-C fascias and soffits it should be done be fore fitting the Guttering , using  fascias and soffits will ensure a good colour match with white FloPlast gutters .  

3. You are now ready to begin installing your gutter start by locating the running outlets above drains or the intended area where the down pipes are to be fitted remember the outlet is where the water will run out of the guttering and as such needs to be as the lowest point  1:600 is the recommended fall  

4. Fix a fascia bracket 100 mm from the running outlet you will need to use more than on screw (do not over tighten screw) ensure bracket is level  

With the outlet repeat this process 100 mm from the furthest point leading to the guttering then fix a string line securely to both brackets (over large distances you will need to support any sagging the line may have in the centre to prevent pooling
At low points).  

5. Now space your brackets to the required distance and fix up to the string  line when deciding on bracket spacing you should remember that in areas of heavy snow fall it is better to fix the brackets closer together This provides more support for the guttering or you can at least put two screws in the fascia  brackets .You will find it makes a neater job to actually measure the centres of brackets used.  

6. Keep screws away from the top of the timber / fascia board as this will avoid splitting  the wood / plastic fascia You should use 10x1.25 screws to fit guttering with two in each bracket .Or one 14 x 1.25 screw should suffice.  

Before fixing gutters you should lubricate all seals this makes fitting the clips 100 percent easier if you do not have any silicone spray and the clips are tight a small smear of washing up liquid will help.  

Ensure gutters are only fitted up to the cut lines as indicated inside the fitting this allows adequate room for the gutter to expand and contract.  

To fit the gutter start at  the out let insert the back edge first up under the retaining clip then push down ward until the front clip fits tightly into place  

Ensure the back clip has remained in position and double check the  gutter  is in the marked position .allowing for expansion and contraction.   

Now add a union to add the next piece of gutter, and repeat the process until all fittings are in place.  

Add stop ends to the end of each gutter run and complete your down pipes 

 FloPlast Compatibility Table

Manufacturer H/R SQ White
Hunter Yes Yes No
Marley Yes No No
Osma Yes No No
Polypipe Yes Yes No
Terrain No No No
Rymway Yes Yes No
Brett Yes No No
Hepworth Yes Yes No
Although size and shape fit there may be some colour difference.


Down Pipe One End Flow Rate Gutter Fixed Level  Gutter Fixed 1.350 Fall 
Litres Sec Area Sq M Litres Sec Area Sq M
76mm Half Round 0.5 24 0.6 29
112mm Half Round 0.9 43 1.3 62
112mm Square Line 1.7 82 2.0 96
Niagara 2.34 112 2.5 122
Deep Flow 2.05 98 2.87 137
Ogee 1.1 53 1.5 72
Down Pipe In Centre Flow Rate Gutter Fixed Level  Gutter Fixed 1.350 Fall 
Litres Sec Area Sq M Litres Sec Area Sq M
76mm Half Round 0.7 34 0.8 38
112mm Half Round 1.8 86 2.6 125
112mm Square Line 3.2 154 3.8 182
Niagara 6.14 294 6.25 292
Deep Flow 3.97 190 5.56 266
Ogee 2.4 115 3.0 144

Gutterin & Drainage FAQ's

What brackets do I use when installing gutter directly to the rafters?
The standard gutter bracket, bolts to the galvanised Top, Side and Rise and Fall Rafter Brackets. Side rafter brackets are simple to fix and they are adjustable after installation  

How do I connect to a neighbour’s different gutter?
FloPlast have a range of adaptors for most applications, you will find these on the ordering page.  

Where would I use a Pedestal Trap?
FloPlast’s pedestal trap new slim line design, fits neatly behind the basin pedestal. 

I am installing a new kitchen appliance but the space under the sink is limited.
Install the TW472 Appliance Half Trap, or the TWT41 Appliance Trap Adaptor to an existing trap.

I need to connect to an existing waste pipe but I am not sure of the size.
FloPlast manufacture a range of Universal compression fittings ‘UNICOM’ which take up any discrepancies in size between different manufacturers or materials.

How do I stop the ‘Gurgling’ effect when I empty my bath?
FloPlast manufacture a range of Air Admittance Valves to overcome this problem. Please refer to our section on Air Admittance Valves within the Soil and Waste pages.  

Do I need to install fire prevention collars when installing a pipe through a wall or floor?
Fire prevention collars are only required when a pipe penetrates through a wall or floor of a neighbouring property, i.e. a block of flats or apartments.  

I am installing a new w.c. pan and the existing Pipe is at a different height to the new outlet.
Use FloPlast SP102 Offset WC Connector, or SP106 Flexible WC Connector.  

I am trying to connect pipes that are at a Non standard angle, how do I do this?
FloPlast have 0-90º Adjustable bends in 32mm and 40mm ‘UNICOM’, and 110mm Underground Drainage.  

What fittings do I need to fit my waste Pipe to my soil pipe?
FloPlast produce a range of boss pipes and adaptors. Please refer to our section on bosses and adaptors. 

Where do I use the new MAC?
The MAC can be used in all situations when access is required, and where the invert level is less than 600mm.  

Where do I use the PPIC?
The PPIC can be used in all situations when access is required, and where the invert level is less than 1000mm.  

Are FloPlast manhole covers load bearing?
FloPlast Manhole Covers are suitable only for pedestrian or light traffic. i.e. for use in paths or driveways.  

Where would I use a BIG?
A back inlet gully can be used where additional installation of waste pipe or rainwater downpipes is required. 

What is the recommendation for access in a drainage system?
Please refer to the Building Regulations, Approved Document H1, Section 2, Table 10. Reference to Access is also covered in our Underground Drainage product brochure.  

I am trying to connect PVC pipes to Clay pipe, what fittings do I need?
FloPlast produce a range of adaptors to suit this situation, please refer to our section on Underground Drainage Adaptors.  

I want to connect 110mm (4") pipe to 160mm (6") pipe.
Use the FloPlast Level Invert Reducer D99.  

What size is cladding available in?
FloPlast cladding is available in two sizes and profiles. 150mm Shiplap, and 100mm V Joint.  

How do I connect Corners, Joints and Trims to fascia and soffit?
FloPlast recomment that the use of Low Modulus Silicone or a proprietary adhesive such as super glue to fix corners, joints and trims.  

The Building Regulations require ventilation of the roof area in certain circumstances, what products are available to comply with these regulations?
FloPlast produce a range of ventilation products, please refer to our section on ventilation products.  

How do I stop the lower section of Sarking felt from rotting?
FloPlast supply an Eaves Protection System, please refer to our section on Ventilation and Eaves Protection.