Question 1

What are the pros and cons of using a double branch versus a Y branch fitting?

Accepted Answer

A double branch is more compact and fits better in tight, vertical stacking layouts, allowing two horizontal inlets into one stack. A ‘Y branch’, on the other hand, gives gentler flow paths (less turbulence and lower blockage risk) but takes up more space.

Question 2

What is a 4-inch branch in UK drainage?

Accepted Answer

In UK practice, a “4 inch branch” usually means a branch fitting for a nominal 110 mm soil pipe.

Question 3

How far apart should branch connections be on a stack?

Accepted Answer

To prevent crossflow, you must leave vertical spacing between branch centres. For small branch pipes (≤ 65 mm), centre spacing is often 110 mm on a 100 mm stack. For larger stacks spacing increases.

Question 4

Can a branch fitting accept waste pipe connections (e.g. from a sink)?

Accepted Answer

Yes. Many branches include bosses that can be drilled and fitted with boss adaptors to accept waste pipes of different sizes (e.g. 32 mm, 40 mm, 50 mm).

Question 5

When would you choose a 135° or 45° branch over 92.5°?

Accepted Answer

Use 135° or 45° when your pipe layout is more linear or when you want gentler flow transitions. They reduce turbulence compared to sharp 92.5° angles, though they require more space and careful design.

Soil pipe branches

Soil Equal Branch 92.5 Black 110mm

110mm Floplast Soil 92.5° (87.5°) Equal Branch Double Socket Black

Osmadrain Single Socket Short Radius Bend 15° 160mm 6D167

Osmasoil 4S291G 110mm Ring-seal Corner Branch 87.5ã…â„¢ Grey

FloPlast Black 110mm Soil 92.5° Triple Solvent Socket Access Branch

Brett Martin Plastic Soil Pipe Push Fit Double Socket Access 92.5 Degree Branch 110mm - Black

Cast Iron Style Soil Pipe 92.5dg Branch 110mm - Anthracite Grey

Cast Iron Style Soil Pipe 92.5dg Bossed Branch 110mm - Anthracite Grey