It was a 16th win in 17 outings this season and with only five games left to play they are in poll position to take the title. They face bottom of the table Tondu in their next game before heading to second placed Ammanford on 26 March for what could be a title decider.
Two Seb Barrett penalties gave Builth an early lead, but no sooner had they gone 6-0 ahead than they were hit by two tries from the visitors. A third Barrett penalty before the break made it 12-9 to the league leaders at the break.
A third Skewen try on the hour left them with 20 minutes to clinch a bonus point. When Builth lost outside half Gavin Jones to a yellow card all the indications pointed to another try for the visitors, but then they lost a forward as well and Barrett kept his cool to land a fourth penalty to earn a losing bonus point for the home side.
All fixtures in the West division were cancelled due to waterlogged pitches, but things were a lot brighter in the North with the eagerly anticipated tie between second placed Bala and third placed Pwllheli the only game succumbing to the inclement weather.
Nant Conwy extended their lead at the top of the table with a 37-3 victory over COBRA to secure their seventh successive league win. A brace of tries from No8 Carwyn Ellis helped the runaway leaders move 19 points clear at the top.
Ifan Pyrs, Gwion Jones, Jack Moriarty, Sion Prince and Aeron Jones also chipped in with tries, although Delwyn Jones could only manage one conversion in the muddy conditions. Llew Williams replied with a first half penalty for the visitors.
Bethesda edged fourth placed Caenarfon 10-5 in a tight affair with Dylan Gwyn scoring the visitors try. Llangefni picked up just their third win of the season after beating fifth place Abergele 9-3.
Three fixtures were completed in Division 1 East. Fifth paced Blaenavon accounted for ninth placed Risca in a match that ended 10-3 with back row forward Marcus Jones scoring the only try of the game from short range and outside half Darren Pearce adding a conversion and penalty.
Brecon trounced Nelson 29-0, with tries coming from Jake Crocket, Gareth Owen and Ryan Harris. In the other fixture to survive the weather Brynmawr defeated Senghenydd 25-10 with wing Tom Ashmead racing in for a hat-trick of tries.
