Valley boards or no valley boards?

[patp]

Our building inspector has just visited and asked that we install valley boards on our tiled bungalow roof. The, very experienced, roofer is not in agreement. We are waiting for the carpenter to revisit to get his opinion. They are saying that no one does this any more. There is polystyrene under there and they say this is sufficient. Any thoughts?

[nod]

You should have valley boards to support the lead Or I’m guessing your fiberglass valley 

[patp]

I phoned the truss manufacturer who tells me that valley boards are designed in nowadays. I think he called them Valley Pieces? Have referred the building inspector to the truss designer to discuss further as I am out of my depth.

[CC45]

see @nod - good answer.

[nod]

5 hours ago, patp said:

I phoned the truss manufacturer who tells me that valley boards are designed in nowadays. I think he called them Valley Pieces? Have referred the building inspector to the truss designer to discuss further as I am out of my depth.

Your not really out of your depth

BC requires you to have valley boards Truss manufacture agrees 

Your the boss Tell The roofer your hands are tied 

[epsilonGreedy]

While researching this topic I read somewhere that one bonus of using substantial valley backing is that the valley (if wide enough) then becomes a useful roofer footpath up to the ridge for maintenance.

[patp]

The truss manufacturer does not agree. The designer says that strength in the valleys is designed in nowadays.

 

The building control officer says that on the BBA certificate of FG valley trays it clearly states that valley boards are needed. He explained that, as @epsilonGreedy says, people will use the valleys as ladders.

 

Roofer has gone off to some homework.

 

After discussion we decided that, as we only do this once, the valley boards are going in. Photos will be taken and the inspector is coming back at first fix to check it all out.

[epsilonGreedy]

4 minutes ago, patp said:

The truss manufacturer does not agree. The designer says that strength in the valleys is designed in nowadays.

 

 

I am struggling to understand how reinforcement backing for the valley can be designed into the trusses. Did your roofer simply lay a grp valley across the tops of trusses 600mm apart? 

 

My roof has a valley but the design and the carpentry to create the valley is down to me and was outside the scope of the truss design. This remains an unresolved question for me hence my interest in your thread. (I am not an expert)

[patp]

I just phoned the designer who said that "nowadays we use valley pieces to strengthen that area" or words to that effect. I think he said that they were smaller as they got near the valley?

 

The roofer has said that no one in the building trade puts valley boards in any more. He said that on one site they were asked to put them in because that builder had experience of aerial installers climbing up the valley. If you look above the building inspector says that the BBA certificate clearly states they are necessary. We have looked at the packaging on the fibreglass trays and there is not anything to say that they need valley boards. Our fibreglass trays are a bit ridged so we wondered if, unbeknown to the BI, they are strengthened in some way? All the trades on site are saying valley boards are not used on big sites. However, as above, we are only doing this once and it is just a couple of sheets of ply, some battens and the labour. Better that now than problems down the line if an albatross lands on the roof!

 

[Andrew]

I have lots of valleys in my complicated roof and valley boards and noggins were always a requirement for everyone involved in the build. They weren't part of the scope of the timber frame contract but I paid the frame erectors directly for a couple of extra days to put them in. They also needed to put in noggins between the rafters so the roofer would have somewhere to fix the ends of the battens as they run into the valley.  This is a photo from last year just before the roofer started. 

 

 

They used a ridged GRP valley trays, but still needed the valley boards. This is one of the valleys mid-way through felting and battening. 

 

 

I too can't really see how the trusses would provide any additional support for the valley or how you can go without valley noggins as otherwise the roofer won't have anywhere to secure the end of the battens (perhaps they just don't get fixed at the end?). 

 

Do you have a photo of the roof as it is without the valley boards? 

[epsilonGreedy]

59 minutes ago, patp said:

I just phoned the designer who said that "nowadays we use valley pieces to strengthen that area" or words to that effect. I think he said that they were smaller as they got near the valley?

 

The roofer has said that no one in the building trade puts valley boards in any more. He said that on one site they were asked to put them in because that builder had experience of aerial installers climbing up the valley....

 

 

I think wires have been crossed here.

 

Years ago truss manufacturers only provided trusses for the main regular segments of a roof and where there was an L-shaped intersection the roof carpenter filled in the missing section of the roof with traditional cut rafters that diminished in length going up the valley. These days the truss manufacturers provide a set mini trusses that infill the L-intersection.

 

I thought we were talking about missing valley boards that support the valley material (GRP or lead). Valley boards can either be continuous lengths of timber running over the top of main trusses and infill trusses or the valley support can be fabricated from multiple flush infill boards shaped to fit between the trusses.

 

I am guessing your building inspector has looked at the spec for the GRP valley and is now saying why are the valley boards missing. Somehow the conversation about missing valleyboards has become conflated with a side discussion about truss infills. There might be a relationship because the valleyboards will connect with the infill trusses. 

Edited February 16, 2021 by epsilonGreedy

[nod]

I’d be starting to think about getting a different roofer 

If the roof leaks he may tell you to get an umbrella ☔️ 

[Temp]

Got me wondering whats on my roof. We have valley tiles..

[CC45]

@temp same with us - still needed timber laid up the valley for the battens to fix to.

 

@patp - as @nod says - get the valleys lined and if your current roofer won't do it then get another one.  There's nothing much going on at the 'big sites' that I'd list as quality - its more about cutting corners to bolster their margin + a lax inspection system.

 

Do it right do it once

[patp]

It wasn't a hard decision to just tell the roofer to get it sorted. To be fair he did not argue, just called the carpenter to come back and put them in. Once we had a decision over the "best" way or the cheaper/easier option we went by our mantra of "we are only doing this once" and so have taken all the advice above.

 

It is common for tradesmen to quote what goes on on big sites. It does them no favours because none of us would choose to buy one those houses if we had the choice.

 

[Temp]

Perhaps make sure he knows how to do lead work or get someone experienced  to do that?

[Oz07]

Always put them in. Worst job in the game. Boring. Ignore dormer had to alter size after it was built to the drawing. 

Edited February 20, 2021 by Oz07

[epsilonGreedy]

@Oz07your second photo above shows a combination of infill valley board pieces plus a continuous run over the rafters. Is that common? Fitted to bring the valley base up to the ideal height for the tiling?

[Oz07]

I used scrap 8x2 off the cut rafters for the infill. Because the valley was built off a lay Board I set the infill 2 or 3 " out from the centre of the valley. I didn't like the gaping hole in the middle so got a thin sheet of ply and ripped it down to smooth this out. GRP valley sits on ply, lath nails into 8x2

 

Some use thin ply for the GRP with 2x2 noggins out outside for lath fixings

[Oz07]

also bonus points for anyone who can see the last common rafters running out on that picture. The extension is built half a brick longer on one wall than the other. I set out off the front wall. Did realise when marking wall plate but kept with set out off front wall incase it effected bond of tiles when setting out from gable. Complete idiots they are. Cant wait till they fit the garage door and the customer realises...