1. Overall
As mentioned, there are differences between NS 8411 and NS 8412 since the latter also includes a phase of prior fabrication, and assembly when agreed.
The manufacturing process and the subsequent assembly require its own provisions, which also apply to the time of delivery. Incidentally, in NS 8412 the term “fulfilment” is used, while NS 8411 uses the term “delivery”.
In this article, we focus on those provisions of NS 8411 and NS 8412 that coincide.
2. Rule mirror

NS 8412 also contains a provision for deadline extension in paragraph 11.4 which is dealt with in the separate thematic collection for NS 8412, and the article itself can be found here.
3. About timely delivery or fulfillment
In the following, we use “delivery” as a common term.
Both standards are based on the fact that the construction product or product must be delivered to “agreed upon time”, see NS 8411 paragraph 13.1 and NS 8412 paragraph 11.3.1.
If the parties have not agreed on delivery by a certain time, the seller shall ensure that the ordered construction products or products are delivered within “reasonable time”.
Since NS 8412 assumes a prior manufacturing process in which the buyer must also be involved, the formulations in NS 8412 paragraph 11.3.1 are somewhat different from those in NS 8411 paragraph 13.1, but the point is in principle the same.
For construction products, it follows from NS 8411 paragraph 13.1, second paragraph that delivery takes place “within a reasonable time after the conclusion of the agreement”whereas in NS 8412 paragraph 11.3.1, second paragraph it states that the seller shall carry out the transaction with “reasonable progress and without unnecessary interruptions”. The same applies if there is also an agreed assembly.
What is “reasonable” in both cases will depend on an overall assessment of several conditions, and what is “reasonable” in one delivery may be thought to be unreasonable in another. In such an overall assessment, there are certainly a number of factors that could come into play.
Since the purchase of construction products concerns something that by definition has been completed at the time of the contract, stricter requirements will be imposed on the seller when considering what is “reasonable time”, than where the seller will manufacture and possibly assemble.
In the overall assessment that must be made when the parties have not agreed on a specific delivery time, the type of construction products or the type of manufacturing in question will be of central importance.
If the buyer has ordered marble tiles produced only in a marble quarry in Italy and has been informed of this at the latest at the conclusion of the contract, the buyer will not be able to expect the tiles to be procured within a few days and perhaps not within a few weeks. On the other hand, the buyer can expect the seller to execute the order as quickly as possible and that the seller follows up his order with the manufacturer.
If it concerns the manufacture of a product where the manufacturing process is no more special than that of “assembly line” production, but according to the buyer's own goals, this may indicate that the assessment of reasonableness is more stringent towards the seller than in the case of complex calculations, extensive detailed design, long delivery time must be input factors, etc.
It will also be relevant to draw in the seller's possible knowledge of the buyer's situation. If the buyer has notified the seller that he needs the construction goods or product then “as fast as possible”, of course, the reasonableness assessment will be different from where the buyer has indicated that he does not need the construction goods or the product before “in a few months”.
The reasonableness assessment is thus more characterized by the fact that the seller is expected to act loyally and show care for the buyer's situation and his needs, than that the seller has a performance obligation.
Note the last sentence of the provisions, which states that the seller must inform the buyer about when delivery can take place, and that this information should be given as follows “as soon as possible”.
The last paragraph of the provision states that the seller can choose when delivery will take place if the agreement specifies delivery within a specified period of time. In other words, it is not the buyer who can demand exact times within the time frame unless otherwise specifically agreed.
4th. Delayed Delivery Notification
Both standards have a separate provision for notification if the seller is delayed, see NS 8411 paragraph 13.2 and NS 8411 paragraph 11.3.2.
In the provisions, the delay is linked to what is “agreed time”.
A natural understanding of this is that the seller has a duty of notification only in cases where delivery has been agreed at a certain time.
However, we prefer to understand that the “agreed time” must be extended to those situations where a specific time for delivery has not been agreed, but where the seller has a duty of care to initiate the necessary “within a reasonable time”. It is at least as important for the buyer to be kept informed by the seller — and especially if the development does not go (completely) as expected. Another thing is that it can become more difficult for buyer to make applicable sanctions against seller when exact delivery time has not been agreed. However, we believe it is easier for the buyer to win if it turns out that the seller has not followed up with the buyer whatsoever.
When such circumstances arise the seller is obliged to notify the buyer “without undue residence”.
This duty of notification raises at least two issues.
First, the question is how sure the seller must be that his duties to the buyer are delayed. Is it enough with a certain suspicion that he may be delayed, or must the seller have been given the certainty that he is certainly going to be delayed? These are, of course, two extremes, and we rather agree that the duty of notification is triggered somewhere in between.
One thing that is for sure is that the seller cannot wait until he has certainty about the exact duration of the delay. It is stated in the last paragraph of the provisions, which establishes that the seller's notification to the buyer of the duration of the delay is something that occurs at a later date.
At the same time, we would consider that as long as the seller has a legitimate reason to believe that a possible delay can be averted, and the seller takes the necessary actions in this regard, then the seller must have the right to do so without notifying his buyers.
At some point, however, the seller will understand that it is more likely that he will be delayed than that this will be averted, and then the duty of notification must occur.
This period we refer to here is the most natural thing to attribute to the condition that the seller must notify the buyer “without undue residence” that he is unable to fulfill within the agreed deadline. As long as the seller tries to clarify whether the delay can be averted, it will be possible to say that there is a reason for the stay.
However, the seller cannot spend all the world's time clarifying before the buyer is notified. The buyer also has interests to attend to, and the buyer may need to make their own adjustments to minimize the consequences of any delay. Under any circumstances, an early notice will allow the buyer to plan alternatives and adjustments for the event that the delay actually becomes a reality.
In the field of contract law, the term is also used “without undue residence” and it is reasonably clarified that this deadline is counted in days and neither weeks nor months.
NS 8411 and NS 8412 regulate the purchase of goods and products for construction projects. They are therefore intended to be applied in the same area of life as the standards of contract law.
It is unfortunate to make different demands on the content of “without undue residence”. It can create undue uncertainty and appear to create conflict. Our view is that “without undue delay” is treated as a legal standard and given the same meaning in NS 8411 and NS 8412 as in, for example, NS 8405 and NS 8407.
This means that as soon as the seller is given reasonable grounds to believe that the agreed delivery time may be exceeded, the buyer must be notified within a few days.
Then the seller must notify the buyer “as soon” him “have sufficient knowledge (...) of when delivery may be effected”, see the last paragraph of NS 8411 paragraph 13.2 and NS 8412 paragraph 11.3.2
We will return to the buyer's possible sanctions against the seller in case of delayed delivery. However, it may be appropriate to point out that the seller's general liability in case of delay is limited to the size of the purchase price. If the seller fails to notify, it follows from the second paragraph of NS 8411 paragraph 13.2 and NS 8412 clause 11.3.2 that the limitation of liability does not apply. That is, failure to notify the seller incurs a risk of having to compensate the buyer's full financial loss and is limited only by the general conditions of compensation. Similarly, the seller risks having to pay compensation in addition to daymulch where daymulch is originally agreed instead of replacement.