We have both and have replaced sections of both--labor cost was identical. The only difference was the cost of the baseboards, but at least where we live, that was not huge. I'd ask for the breakdown between labor and materials. Taller does cost more and that could add up across a big house depending on the material, but that still sounds like a lot. The only think I can think of that might be extra labor is that if you're working with a builder who has standard sizes for ceiling heights and trim, they might have stock door casings and would need to cut those down to accommodate 7 1/4" baseboards...?

So there is a trim carpenter out there that doesn't have a compound mitre saw?

I realize that things are different in different build environments and regions. But sometimes it seems like pros tend to justify costs. Certainly they have more experience than customers but there is a bias towards explaining away all high cost things. I think some of this is natural and expected.

I have not had labor upcharges based on size within basic parameters like 5in to 7in. I have also installed larger baseboards myself and don't find it significantly more time consuming. I find the difference between painting 5in and 7in to be insignificant.

At some point, it doesn't matter. The builder quotes and the buyer pays or doesn't pay. In this case, it may be a significant profit item or it maybe that he has to use a different crew (really doubtful but possible I guess).

You don't cut anything with bigger trim (at least in my region) - the trim stops at the door casing. If you scribe the corners - that is definitely harder. So there isn't zero difference but $3000 seems excessive in my world.

Is this a totally custom home i.e. on an individual lot, specific design to lot, you interact directly with the builder? Or is this a new build within a new subdivision and you interact with a site supervisor? I'm guessing the second since you mentioned "builder's standard size." If so, the labor isn't going to be only the installers' labor. It will be the office workers' labor to change your contract, order/negotiate a price for a product that is not usually ordered, the labor to receive that product and get it to the right house at the right time and if there is a delay from normal process, the labor to make sure the trim crew can be there when it arrives plus what @Jeffery R Grenz said above.

Even if a totally custom home, option 1 above, there is effort involved in changing the original quote/contract, ordering materials, perhaps returning materials (you didn't say how far along this was), making sure the trim carpenter has the skill to install. The change might even slow down the process, making the site supervisor spend time (labor) reorganizing the painters who will come in behind the trim carpenter.

Not sure which rooms you are planning this change in, but once taller trim is installed, you increase the risk of nicking plumbing in rooms that have plumbing so you need a skilled installer.

Nothing is ever just one thing. Building a house is a process of increasing complexity in today's time. Builders have always had a "change order" charge that is mostly valid because of the above, but is also a notice to make the client really consider changes once the process is underway.

Not sure who is carrying the construction loan on this house, you or the builder, but if it's the builder and completion gets extended from original date, the interest incurred on the loan is another charge that has to be covered.

IMO, 10' ceilings definitely need larger trim so I would go for the change. But, make sure you have reviewed all the plans and you aren't going to make anymore changes that might cost even more. The first change is going to be $3K, the second even more. It's a technique builders use to keep the process moving i.e. changes get increasingly more expensive as the build progresses and can you really blame them? It's a business.

We currently have 5 1/4” baseboard as part of builders standard size and want to upgrade to 7 1/4” …

First question is, Is this a wise choice? It's not just a matter of "bigger is always better" -- which, by the way, is not a universal truth. You want things to be proportional, and the rule for baseboards is 7% of the height of the room.

Second question I'd ask, Just how important is the baseboard to you? Personally, it'd be kinda low on my list of concerns.

Labor cost dif is more than material cost dif.
5" is almost a common standard & easily cut w a standard mitre saw.
7" isn't always in stock, is 40% larger surface to paint, 40% heavier & requires a compound mitre saw.

I initially agreed with the OP, but I accept your knowledgable comments. Sometimes things aren't always obvious to the casual observer. To give an example from my own bank of knowledge, I have been baking wedding cakes for decades, and a larger cake is considerably more work (takes more skill) than smaller cakes. Complex shapes are more time consuming to decorate, though they require no more icing. And I will not bake a square cake; it's just not worth my time. But I understand that a noice baker wouldn't see these as more difficult things. It's just more batter and more time in the oven, right?

Is this a totally custom home i.e. on an individual lot, specific design to lot, you interact directly with the builder? Or is this a new build within a new subdivision and you interact with a site supervisor?

Yeah, I was wondering about that too. When you're talking about a subdivision builder, upcharges are how they make their money.

Another thing that can be true: Maybe the builder just plain doesn't want to do it, and he's priced it high-high-high to discourage you.

So many good points made by tozmo and Jeff G.

I would pay the difference if you want the proportions right. A 10' ceiling begs for taller baseboard--what type and profile are you using? Is it one piece or more? My 95+ year old house has 8' (gasp!) ceilings and 3-piece baseboards, consisting of a 1x6, a 2" ogee base cap, and a decorative base shoe molding (not a quarter-round). So it's about 8" tall and gives a nice base to the walls. I think a 5" is going to look skimpy on a 10' ceiling.

IMO changes once construction is started always cost not just in materials but as mentioned often affect other things.

Maybe it's just me, but 7" baseboards feel way too heavy, even with 10' ceilings. I don't feel baseboards add much to the style of the room and are more for practicality.

Only worth considering if the style of the house is very traditional, with somewhat ornate millwork elsewhere. The more modern your style, the less baseboard really matters.

Thanks all!

It is definitely on the modern / contemporary side with essentially just a straight edge baseboard and none of the decorative details like in a traditional piece. Even the shoe mold would be a thin flat profile vs a quarter round. If we go with the 5” now, is it possible to add an extender or cap some point later to add another 2-3”?

I can appreciate the change order causing increased costs but we are still at least a month away from dry wall so didn’t think it would be a too big of an issue to bring up at this point. But yes understand this is where the margin magic happens also.

If we go with the 5” now, is it possible to add an extender or cap some point later to add another 2-3”?

Likely not. Certainly not if the additions add to the overall thickness of the assembly. Because you do not want the baseboard to stand proud of the door casings. Door casings should be proud of the base and usually are about 1/8" thicker than base mouldings.

I would expect a labor upcharge. Wider is heavier, less flexible, more work & skill to cope corners, more subject to bowing & twisting (If using real wood vs mdf), more (MDF?!) dust, more wear & tear on tools and labor. requires a larger, heavier crosscut saw that require bigger, more expensive blades.... As Jeff mentioned the 40% heavier, etc, I would expect at least a 40% labor upcharge minimum before any PIA premium added just because labor would rather not deal with it.

A Modern home shouldn't even have baseboard. Much less a giant too froofy compound one. It should have had a museum reveal, no crown, and no window trim either.

Let me add to the differences. My baseboard installers are skilled finish carpenters, not the last minute bothered task of a hurried flooring installer.

They scribe the base to the floor to minimize gaps. Takes more time with the heavier base.

I generally design modern homes, and while we're not in the no-baseboard price range, we do use a squared-off 3-inch molding most of the time. Just enough to cover flooring gaps, ceiling heights be darned.

" I can appreciate the change order causing increased costs but we are still at least a month away from dry wall so didn’t think it would be a too big of an issue to bring up at this point "

They also need to plan, probably change the order with the supply house (maybe even special order). Change the paperwork for the trim carpenter and for the super. Unfortunately when they build a lot of this is repetitive and if they do not dot their I's and cross their T's it gets messed up.

Considering that you have a modern home, disregard what I posted. My baseboards would not be appropriate for your home.

Just another data point on the difference in materials cost - we are doing 5 1/2" baseboards upstairs and 7 1/2" downstairs. Purchased finger-jointed primed poplar from a local sawmill (one that has done a lot of recent work with This Old House, another couple renovation shows, etc. and has the associated reputation/name recognition that one often finds included in costs). 5 1/2" cost $1.89 a foot while the 7 1/2" jumped up to $3.35 a foot. The 5 1/2" was in stock but the 7 1/2" was a special order item that took about 3 weeks for them to complete. I can't speak to the impact on labor since ours was known from the beginning, but thought an insight to the materials cost might be helpful.

I also realize, reading this thread, that much of this may be regional. 7" baseboards are very common in my area--most houses on my block have them--and we can go to the lumber yard around the corner and find it in stock easily in standard profiles. But in areas with newer housing stock I can imagine it might not be regularly purchased or stocked. Consequently, finish carpenters in our area are accustomed to working with trim that size, so presumably already have the tools necessary, whereas those in areas where it's rare may not. OP's area may be one of the latter. And I guess we have lucked out that we've never had an upcharge for the weight--that aspect didn't even cross my mind (despite the fact that I've had to move both with some frequency!)

Litmus test:

if the cost differences were negligible, the tract builders & flippers would use it. This goes for almost every option.

I'm actually not sure that litmus test holds here--plenty of multi-million dollar new builds in my area don't use tall baseboards because they don't work well for many modern aesthetics--nothing to do with cost. Almost all the flips here in recent years are going for modern, even if the house doesn't call for that at all. We have a 110-year-old home so it's appropriate (and original) there but I wouldn't choose it for a modern or even a mid-century home. Our house originally had 7 1/4" in most rooms and 5 1/2" in closets and the bathroom; we went down to 4 1/2" in a new bathroom we added just because I thought it looked better in the context of the room, even though it was a tiny space so cost was moot.